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64-bit Intel® Xeon™ Processor MP
with 1 MB L2 Cache
Thermal/Mechanical Design Guidelines
March 2005
Document Number: 306750-001
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Intel may make changes to specifications and product descriptions at any time, without notice.
Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Intel reserves these for
future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them.
The Intel Pentium and Xeon processors may contain design defects or errors known as errata, which may cause the product to deviate from published
specifications. Current characterized errata are available upon request.
Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.
Copies of documents, which have an order number and are referenced in this document, or other Intel literature, may be obtained by calling 1-800-5484725, or by visiting Intel's Web Site.
Intel, Pentium and Xeon are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries.
Copyright © 2005, Intel Corporation. All rights reserved.
* Other brands and names may be claimed as the property of others.
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Contents
1
Introduction ....................................................................................................................... 7
1.1
Objective ................................................................................................................ 7
1.2
Scope ..................................................................................................................... 7
1.3
References............................................................................................................. 7
1.4
Definition of Terms ................................................................................................. 8
2
Thermal/Mechanical Reference Design .......................................................................... 9
2.1
Mechanical Requirements ..................................................................................... 9
2.1.1 Performance Target .................................................................................. 9
2.1.2 Critical Interface Dimensions (CID) ........................................................ 10
2.2
Thermal Requirements ........................................................................................ 11
2.2.1 Thermal Profile........................................................................................ 11
2.2.2 TCONTROL Definition .................................................................................. 13
2.2.3 Performance Targets .............................................................................. 14
2.3
Characterizing Cooling Solution Performance Requirements ............................. 15
2.3.1 Fan Speed Control.................................................................................. 15
2.3.2 Processor Thermal Characterization Parameter Relationships.............. 16
2.3.3 Chassis Thermal Design Considerations................................................ 18
2.4
Thermal/Mechanical Reference Design Considerations ..................................... 19
2.4.1 Heatsink Solutions .................................................................................. 19
2.4.2 Thermal Interface Material ...................................................................... 19
2.4.3 Summary................................................................................................. 20
2.4.4 Assembly Overview of the Intel Reference Thermal
Mechanical Design.................................................................................. 20
2.4.5 Thermal Solution Performance Characteristics ...................................... 21
2.4.6 Structural Considerations of Cooling Solution ........................................ 22
2.4.7 Components Overview............................................................................ 23
A
Mechanical Drawings ..................................................................................................... 27
B
Testing Methods.............................................................................................................. 37
B.1
Case Measurement.............................................................................................. 37
B.2
Supporting Test Equipment ................................................................................. 37
B.3
Thermal Calibration and Controls ........................................................................ 38
B.4
IHS Groove .......................................................................................................... 38
B.5
Thermocouple Conditioning and Preparation ...................................................... 39
B.6
Thermocouple Attachment to the IHS.................................................................. 40
B.7
Curing Process..................................................................................................... 43
B.8
Thermocouple Wire Management........................................................................ 43
B.9
Local Air Thermocouple Placement..................................................................... 45
C
Safety Requirements ...................................................................................................... 47
D
Quality and Reliability Requirements ........................................................................... 49
D.1
Intel Verification Criteria for the Reference Designs............................................ 49
D.1.1 Reference Heatsink Thermal Verification ............................................... 49
D.1.2 Environmental Reliability Testing............................................................ 49
D.1.3 Material and Recycling Requirements .................................................... 51
E
Enabled Suppliers Information...................................................................................... 53
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F
Processor Thermal Management Logic and Thermal Monitor Features................... 55
F.1
Thermal Management Logic and Thermal Monitor Feature ................................ 55
F.1.1 Processor Power Dissipation .................................................................. 55
F.1.2 Thermal Monitor Implementation ............................................................ 55
F.1.3 Operation and Configuration................................................................... 57
F.1.4 Thermal Monitor 2................................................................................... 57
F.1.5 System Considerations ........................................................................... 58
F.1.6 Operating System and Application Software Considerations ................. 58
F.1.7 Legacy Thermal Management Capabilities ............................................ 59
F.1.8 Cooling System Failure Warning ............................................................ 61
Figures
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
A-1
A-2
A-3
A-4
A-5
A-6
A-7
A-8
A-9
A-10
A-11
A-12
B-1
B-2
B-3
B-4
B-5
B-6
B-7
B-8
4
Critical Interface Dimensions (Sheet 1 of 2) ........................................................ 10
Critical Interface Dimensions (Sheet 2 of 2) ........................................................ 11
Thermal Profile Diagram ...................................................................................... 12
TCONTROL and Thermal Profile Interaction ............................................................. 13
Thermal Profile for the 64-bit Intel® Xeon™ Processor MP
with 1 MB L2 Cache............................................................................................. 14
TCONTROL and Fan Speed Control ......................................................................... 15
Processor Thermal Characterization Parameter Relationships........................... 17
Exploded View of Cooling Solution Thermal Solution Components .................... 21
2U+ Cooling Solution Heatsink Thermal Performance ........................................ 22
Isometric View of the 2U+ Cooling Solution Heatsink ......................................... 23
Hat Spring Isometric View.................................................................................... 25
Isometric View of Hat Spring Attachment to the Base Board .............................. 25
2U Cooling Solution Heatsink (Sheet 1 of 4) ....................................................... 28
2U Cooling Solution Heatsink (Sheet 2 of 4) ....................................................... 28
2U Cooling Solution Heatsink (Sheet 3 of 4) ....................................................... 29
2U Cooling Solution Heatsink (Sheet 4 of 4) ....................................................... 29
Cooling Solution Hat Spring (Sheet 1 of 3).......................................................... 30
Cooling Solution Hat Spring (Sheet 2 of 3).......................................................... 30
Cooling Solution Hat Spring (Sheet 3 of 3).......................................................... 31
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 1 of 5)................................................................... 32
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 2 of 5)................................................................... 33
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 3 of 5)................................................................... 34
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 4 of 5)................................................................... 34
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 5 of 5)................................................................... 35
IHS Groove .......................................................................................................... 38
Groove to Pin Indicator ........................................................................................ 39
IHS Groove .......................................................................................................... 39
Bending Tip of Thermocouple.............................................................................. 40
Securing Thermocouple Wires with Kapton* Tape .............................................. 41
Thermocouple Bead Placement........................................................................... 41
Thermocouple Placement .................................................................................... 41
3D Micromanipulator to Secure Bead Location ................................................... 42
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B-9
B-10
B-11
B-12
B-13
B-14
B-15
B-16
B-17
D-1
D-2
F-1
F-2
F-3
F-4
Measuring Resistance between Thermocouple and IHS .................................... 42
Applying the Adhesive on the Thermocouple Bead............................................. 42
Thermocouple Wire Management in the Groove................................................. 43
Removing Excess Adhesive from the IHS ........................................................... 44
Filling the Groove with Adhesive.......................................................................... 44
Thermocouple Wire Management........................................................................ 45
Local Air Thermocouple Placement for Passive Heatsinks ................................. 45
Local Air Thermocouple Placement for Active Heatsinks (Side View) ................ 46
Local Air Thermocouple Placement for Active Heatsinks (Plan View) ................ 46
Random Vibration PSD........................................................................................ 49
Shock Acceleration Curve.................................................................................... 50
Thermal Sensor Circuit ........................................................................................ 56
Concept for Clocks under Thermal Monitor Control ............................................ 56
Thermal Monitor 2 Frequency and Voltage Ordering .......................................... 58
On-Die Thermal Diode Sensor Time Delay ......................................................... 60
2-1
2-2
2-3
2-4
A-1
B-1
Performance Target Table (Sheet 1 of 2) .............................................................. 9
Performance Target Table (Sheet 2 of 2) ............................................................ 14
Fan Speed Control, TCONTROL and TDIODE Relationship ........................................ 16
Recommended Thermal Grease Dispense Weight ............................................. 24
Mechanical Drawing List ...................................................................................... 27
Test Equipment .................................................................................................... 37
Tables
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Revision History
Revision
Number
001
Description
•
Initial release of the document.
Date
March 2005
Note: Not all revisions may be published.
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1
Introduction
1.1
Objective
This guide describes the reference thermal/mechanical solution and design parameters required for
the 64-bit Intel® Xeon™ processor MP with 1 MB L2 cache. It is also the intent of this document to
comprehend and demonstrate the processor cooling solution features and requirements.
Furthermore, this document provides an understanding of the processor thermal characteristics, and
discusses guidelines for meeting the thermal/mechanical requirements imposed on the entire life of
the processor. The thermal/mechanical solutions described in this document are intended to aid
component and system designers to develop and evaluate a processor compatible solution.
1.2
Scope
The thermal/mechanical solutions described in this document pertain only to a solution(s) intended
for use with the 64-bit Intel Xeon processor MP with 1 MB L2 cache in 2U+ form factor systems.
This document contains the mechanical and thermal requirements of the processor (or processor
family) cooling solution. In case of conflict, the data in the 64-bit Intel® Xeon™ Processor MP with
1 MB L2 Cache Datasheet supersedes any data in this document. Additional information is provided
as a reference in the appendix section(s).
1.3
References
Material and concepts available in the following documents may be beneficial when reading this
document.
Document
®
Comment
64-bit Intel Xeon™ Processor MP with 1MB L2 Cache Datasheet
http://developer.intel.com
mPGA604 Socket Design Guidelines
http://developer.intel.com
®
http://developer.intel.com
®
http://developer.intel.com
®
http://developer.intel.com
64-bit Intel Xeon™ Processor MP with 1MB L2 Cache Processor
Cooling Solution Mechanical Models
64-bit Intel Xeon™ Processor MP with 1MB L2 Cache Mechanical
Models
64-bit Intel Xeon™ Processor MP with 1MB L2 Cache Thermal Test
Vehicle and Cooling Solution Thermal Models
European Blue Angel Recycling Standards
Thin Electronics Specification (Server System Infrastructure (SSI)
Specification) for Rack Optimized Servers
NOTE:
http://www.blauer-engel.de
www.ssiforum.com
Contact your Intel field sales representative for the latest revision and order number of this document.
64-bit Intel® Xeon™ Processor MP with 1 MB L2 Cache
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Introduction
1.4
Definition of Terms
Term
8
Description
Bypass
Bypass is the area between a passive heatsink and any object that can act to form a duct.
For this example, it can be expressed as a dimension away from the outside dimension of
the fins to the nearest surface.
FMB
Flexible Motherboard Guideline: an estimate of the maximum value of a processor
specification over certain time periods. System designers should meet the FMB values to
ensure their systems are compatible with future processor releases.
FSC
Fan Speed Control
IHS
Integrated Heat Spreader: a component of the processor package used to enhance the
thermal performance of the package. Component thermal solutions interface with the
processor at the IHS surface.
mPGA604
The surface mount Zero Insertion Force (ZIF) socket designed to accept the 64-bit Intel
Xeon™ processor MP with 1 MB L2 cache.
PMAX
The maximum power dissipated by a semiconductor component.
ΨCA
Case-to-ambient thermal characterization parameter (psi). A measure of thermal solution
performance using total package power. Defined as (TCASE – TLA) / Total Package Power.
Heat source should always be specified for Ψ measurements.
ΨCS
Case-to-sink thermal characterization parameter. A measure of thermal interface material
performance using total package power. Defined as (TCASE – TS) / Total Package Power.
ΨSA
Sink-to-ambient thermal characterization parameter. A measure of heatsink thermal
performance using total package power. Defined as (TS – TLA) / Total Package Power.
TCASE
The case temperature of the processor, measured at the geometric center of the topside of
the IHS.
TCASE_MAX
The maximum case temperature as specified in a component specification.
TCC
Thermal Control Circuit: Thermal monitor uses the TCC to reduce the die temperature by
using clock modulation when the die temperature is very near its operating limits.
TCONTROL
A processor unique value, which defines the lower end of the thermal profile and is
targeted to be used in fan speed control mechanisms.
Offset
A value programmed into each processor during manufacturing that can be obtained by
reading IA_32_TEMPERATURE_TARGET MSR. This is a static and a unique value.
TDP
Thermal Design Power: Thermal solution should be designed to dissipate this target power
level. TDP is not the maximum power that the processor/chipset can dissipate.
Thermal Monitor
A feature on the processor that can keep the processor’s die temperature within factory
specifications under nearly all conditions.
Thermal Profile
Line that defines case temperature specification of a processor at a given power level.
TIM
Thermal Interface Material: The thermally conductive compound between the heatsink and
the processor case. This material fills the air gaps and voids, and enhances the transfer of
the heat from the processor case to the heatsink.
TLA
The measured ambient temperature locally surrounding the processor. The ambient
temperature should be measured just upstream of a passive heatsink or at the fan inlet for
an active heatsink.
TSA
The system ambient air temperature external to a system chassis. This temperature is
usually measured at the chassis air inlets.
U
A unit of measure used to define server rack spacing height. 1U is equal to 1.75 in, 2U
equals 3.50 in, etc.
®
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Thermal/Mechanical Reference
Design
2.1
Mechanical Requirements
The mechanical performance of the processor cooling solution satisfies the requirements and
volumetric keepouts as described in this section.
2.1.1
Performance Target
Table 2-1. Performance Target Table
Parameter
Minimum
Maximum
Unit
Refer to drawings
in Appendix A
Volumetric Requirements
and Keepouts
1000
g
2.2
lbs
44
222
N
10
50
lbf
44
288
N
10
65
lbf
222 N + 0.45 kg * 100 G
50 lbf (static) + 1 lbm * 100 G
N
288 N + 0.45 kg * 100 G
65 lbf (static) + 1 lbm * 100 G
N
445
N
100
lbf
Heatsink Mass
Static Compressive Load
Dynamic Compressive
Load
Transient
Notes
lbf
lbf
1, 2, 3, 4
1, 2, 3, 5
1, 3, 4, 6, 7
1, 3, 5, 6, 7
1, 3, 8
NOTES: In the case of a discrepancy, the most recent processor datasheet supersedes targets listed in the
above table.
1. These specifications apply to uniform compressive loading in a direction perpendicular to the IHS top
surface.
2. This is the minimum and maximum static force that can be applied by the heatsink and retention solution to
maintain the heatsink and processor interface.
3. These parameters are based on limited testing for design characterization. Loading limits are for the
package only and do not include the limits of the processor socket.
4. This specification applies for thermal retention solutions that allow baseboard deflection.
5. This specification applies either for thermal retention solutions that prevent baseboard deflection or for the
Intel enabled reference solution.
6. Dynamic loading is defined as an 11 ms duration average load superimposed on the static load
requirement.
7. Experimentally validated test condition used a heatsink mass of 1 lbm (~0.45 kg) with 100 G acceleration
measured at heatsink mass. The dynamic portion of this specification in the product application can have
flexibility in specific values, but the ultimate product of mass times acceleration should not exceed this
validated dynamic load (1 lbm x 100 G = 100 lb).
8. Transient loading is defined as a 2 second duration peak load superimposed on the static load requirement,
representative of loads experienced by the package during heatsink installation.
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2.1.2
Critical Interface Dimensions (CID)
The CID drawing illustrates the key interfaces between the package and the thermal/mechanical
solution for the processor. Should there be any conflict, this drawing is superseded by the drawing
in the processor datasheet.
Figure 2-1.Critical Interface Dimensions (Sheet 1 of 2)
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Figure 2-2. Critical Interface Dimensions (Sheet 2 of 2)
2.2
Thermal Requirements
In order to remain within a certain case temperature (TCASE) specification to achieve optimal
operation and long-term reliability, the thermal specification methodology, referred to as the thermal
profile, is used. The intent of the thermal profile specification is to support acoustic noise reduction
through fan speed control and ensure the long-term reliability of the processor. For information on
thermal testing, please see Appendix B.
To ease the burden on thermal solutions, the Thermal Monitor feature and associated logic have
been integrated into the silicon of the processor. By taking advantage of the Thermal Monitor
feature, system designers may reduce thermal solution cost by designing to Thermal Design Power
(TDP) instead of maximum power. The TDP is defined as the power level at which the processor
thermal solutions be designed to dissipate. TDP is not the maximum power that the processor can
dissipate. TDP is based on measurements of processor power consumption while running various
high power applications. This data set is used to determine those applications that are interesting
from a power perspective. These applications are then evaluated in a controlled thermal environment
to determine their sensitivity to activation of the thermal control circuit. This data set is then used to
derive the TDP targets published in the processor datasheet. Thermal Monitor can protect the
processor in rare workload excursions above TDP. Therefore, thermal solutions should be designed
to dissipate the target TDP level.
The relationship between TDP to the thermal profile, and thermal management logic and thermal
monitor features, is discussed in the sections to follow. The thermal management logic and thermal
monitor features are discussed in extensive detail in Appendix F.
2.2.1
Thermal Profile
The thermal profile is a linear line that defines the relationship between a processor’s case
temperature and its power consumption as shown in Figure 2-3. The equation of the thermal profile
is defined as:
y = ax + b
64-bit Intel® Xeon™ Processor MP with 1 MB L2 Cache
Thermal/Mechanical Design Guidelines
Equation 1
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Thermal/Mechanical Reference Design
Where:
y = Processor case temperature, TCASE (°C)
x = Processor power consumption (W)
a = Case-to-ambient thermal resistance, ΨCA (°C/W)
b = Processor local ambient temperature, TLA (°C)
Figure 2-3. Thermal Profile Diagram
TTCASE
MAX
CASEMAX
T
MAX
CASE
TCASEMAX
@
Pcontrol_base
Thermal Profile
@Pcontrol_Base
TCASE
Pcontrol_Base
TDP
Power
The higher end point of the Thermal Profile represents the processor’s TDP and the associated
maximum case temperature (TCASEMAX). The lower end point of the Thermal Profile represents the
power value (Pcontrol_base) and the associated case temperature (TCASEMAX@Pcontrol_base) for
the lowest possible theoretical value of TCONTROL (see Section 2.2.3). This point is also associated
with the TCONTROL value defined in Section 2.2.2. The slope of the Thermal Profile line represents
the case-to-ambient resistance of the thermal solution with the y-intercept being the local processor
ambient temperature. The slope of the Thermal Profile is constant between PCONTROL BASE and TDP,
which indicate that all frequencies of a processor defined by the Thermal Profile will require the
same heatsink case-to-ambient resistance.
To satisfy the Thermal Profile specification, a thermal solution must be at or below the Thermal
Profile line for the given processor when its diode temperature is greater than TCONTROL (refer to
Section 2.2.2). The Thermal Profile allows the customers to make a trade-off between the thermal
solution case-to-ambient resistance and the processor local ambient temperature that best suits their
platform implementation (refer to Section 2.3.3). There can be multiple combinations of thermal
solution case-to-ambient resistance and processor local ambient temperature that can meet a given
Thermal Profile. If the case-to-ambient resistance and the local ambient temperature are known for a
specific thermal solution, the Thermal Profile of that solution can easily be plotted against the
Thermal Profile specification. As explained above, the case-to-ambient resistance represents the
slope of the line and the processor local ambient temperature represents the y-axis intercept. Hence
the TCASE values of a specific solution can be calculated at the TDP and Pcontrol_base power levels.
Once these points are determined, they can be joined by a line, which represents the Thermal Profile
of the specific solution. If that line stays at or below the Thermal Profile specification, then that
particular solution is deemed as a compliant solution.
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2.2.2
TCONTROL Definition
TCONTROL is a temperature specification based on a temperature reading from the processor’s thermal
diode. TCONTROL defines the lower end of the Thermal Profile line for a given processor, and it can
be described as a trigger point for fan speed control implementation. The value for TCONTROL is
calibrated in manufacturing and configured for each processor individually. For the 64-bit Intel
Xeon processor MP with 1 MB L2 cache, the Tcontrol value is obtained by reading a processor
model specific register (MSR) and adding this offset value to a base value. The equation for
calculating TCONTROL is:
TCONTROL = TCONTROL_BASE + Offset
Equation 2
Where:
TCONTROL_BASE = A fixed base value defined for a given processor generation as published
in the processor datasheet.
Offset
= A value programmed into each processor during manufacturing that can
be obtained by reading the IA32_TEMPERATURE_TARGET MSR.
This is a static and a unique value.
The TCONTROL_BASE value for this processor is 50°C. The Offset value, which depends on several
factors (i.e. leakage current) can be any number between 0 and (TCASEMAX - TCONTROL-BASE).
Figure 2-4 depicts the interaction between the Thermal Profile and TCONTROL for an Offset value that
is greater than 0 (i.e. TCONTROL greater than TCONTROL_BASE).
Figure 2-4. TCONTROL and Thermal Profile Interaction
MAX
TTCASE
CASEMAX
TCASEMAX @
T CASE @
TCONTROL
TCONTROL
2
1
Thermal Profile
TCASE
@
CASE
TTCASE
MAX
@
Pcontrol_base
Pcontrol_base
Pcontrol_base
Pcontrol
Power
TDP
Since TCONTROL is a processor diode temperature value, an equivalent TCASE temperature must be
determined to plot the TCASE MAX @ TCONTROL point on the Thermal Profile graph. Location 1 on
the Thermal Profile represents a TCASE value corresponding to an Offset of 0 (the theoretical
minimum for the given processor family). Any Offset value greater than 0 moves the point where
the Thermal Profile must be met upwards, as shown by location 2 on the graph. If the diode
temperature is less than TCONTROL, the case temperature is permitted to exceed the Thermal Profile,
but the diode temperature must remain at or below TCONTROL. In other words, there is no TCASE
specification for the processor at power levels less than Pcontrol. The thermal solution for the
processor must be able to keep the processor’s TCASE at or below the TCASE values defined by the
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Thermal Profile between the TCASEMAX@TCONTROL and TCASEMAX points at the corresponding
power levels.
Refer to Section 2.3.1 for the implementation of the TCONTROL value in support of fan speed control
(FSC) design to achieve better acoustic performance.
2.2.3
Performance Targets
The Thermal Profile specification for this processor is published in the 64-bit Intel® Xeon™
Processor MP with 1 MB L2 Cache Datasheet. The Thermal Profile specification is shown as a
reference in the subsequent discussions.
Figure 2-5. Thermal Profile for the 64-bit Intel® Xeon™ Processor MP with 1 MB L2 Cache
NOTE:
®
The thermal specification shown in this graph is for reference only. Refer to the 64-bit Intel Xeon™
Processor MP with 1 MB L2 Cache Datasheet for the Thermal Profile specification. In case of conflict,
the data information in the datasheet supersedes any data in this figure.
Table 2-2 describes thermal performance targets for the processor cooling solution enabled by Intel.
Table 2-2. Performance Target Table (Sheet 1 of 2)
Parameter
Maximum
Unit
Notes
Mean + 3 σ (non-uniform heating)
ΨCA
0.299
°C/W
Pressure Drop
0.15
In. H2O
Altitude
Sea-level
Airflow
23
CFM
TIM-2 Dispense
Weight
400
mg
Shin-Etsu*G751. Dispense weight
is an approximate target.
50
222
lbf
N
Generated by the cooling solution.
TIM-2 Compressive
Load
14
Minimum
33
147
Heatsink designed at 0 meters
Airflow through the heatsink fins
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Table 2-2. Performance Target Table (Sheet 2 of 2)
Parameter
Minimum
Maximum
Unit
Notes
TCASE_MAX
73
°C
In case of conflict, datasheet
supercedes TMDG.
TCASE_MAX @
Pcontrol_base
50
°C
Pcontrol_base = 20 W
TLA
40
°C
TDP
110
W
In case of conflict, datasheet
supercedes TMDG.
2.3
Characterizing Cooling Solution Performance
Requirements
2.3.1
Fan Speed Control
Fan speed control (FSC) techniques to reduce system level acoustic noise are a common practice in
server designs. The fan speed is one of the parameters that determine the amount of airflow
provided to the thermal solution. Additionally, airflow is proportional to a thermal solution’s
performance, which consequently determines the TCASE of the processor at a given power level.
Since the TCASE of a processor is an important parameter in the long-term reliability of a processor,
the FSC implemented in a system directly correlates to the processor’s ability to meet the Thermal
Profile and hence the long-term reliability requirements. For this purpose, the parameter called
TCONTROL as explained in Section 2.2.2, is to be used in FSC designs to ensure that the long-term
reliability of the processor is met while keeping the system level acoustic noise down. Figure 2-6
depicts the relationship between TCONTROL and FSC methodology.
Figure 2-6. TCONTROL and Fan Speed Control
MAX
CASEMAX
TTCASE
TCASEMAX@T
T CASE @CONTROL
TCONTROL
2
1
Thermal Profile
TCASE
@
TTCASE
CASEMAX@
Pcontrol_base
Pcontrol_base
Fan speed control region
Pcontrol_base
Pcontrol
Power
TDP
Once the TCONTROL value is determined as explained earlier, the thermal diode temperature reading
from the processor can be compared to this TCONTROL value. A fan speed control scheme can be
implemented as described in Table 2-3 without compromising the long-term reliability of the
processor.
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Table 2-3. Fan Speed Control, TCONTROL and TDIODE Relationship
Condition
FSC Scheme
TDIODE ≤ TCONTROL
FSC can adjust fan speed to maintain TDIODE ≤ TCONTROL (low acoustic region).
TDIODE > TCONTROL
FSC should adjust fan speed to keep TCASE at or below the Thermal Profile
specification (increased acoustic region).
There are many different ways of implementing fan speed control, including FSC based on
processor ambient temperature; FSC based on processor thermal diode temperature (TDIODE) or a
combination of the two. If FSC is based only on the processor ambient temperature, low acoustic
targets can be achieved under low ambient temperature conditions. However, the acoustics cannot
be optimized based on the behavior of the processor temperature. If FSC is based only on the
thermal diode, sustained temperatures above TCONTROL, drives fans to maximum RPM. If FSC is
based both on ambient and thermal diode, ambient temperature can be used to scale the fan RPM
controlled by the thermal diode. This would result in an optimal acoustic performance. Regardless
of which scheme is employed, system designers must ensure that the Thermal Profile specification
is met when the processor diode temperature exceeds the TCONTOL value for a given processor.
2.3.2
Processor Thermal Characterization Parameter
Relationships
The idea of a “thermal characterization parameter”, Ψ (psi), is a convenient way to characterize the
performance needed for the thermal solution and to compare thermal solutions in identical
conditions (heating source, local ambient conditions). A thermal characterization parameter is
convenient in that it is calculated using total package power, whereas actual thermal resistance, θ
(theta), is calculated using actual power dissipated between two points. Measuring actual power
dissipated by the heatsink is difficult since some of the power is dissipated via heat transfer into the
socket and board. Be aware, however, of the limitations of lumped parameters such as Ψ when it
comes to a real design. Heat transfer is a three-dimensional phenomenon that can rarely be
accurately and easily modeled by lump values.
The case-to-local ambient thermal characterization parameter value (ΨCA) is used as a measure of
the thermal performance of the overall thermal solution that is attached to the processor package. It
is defined by the following equation, and measured in units of °C/W:
ΨCA = (TCASE - TLA) / TDP
Equation 3
Where:
ΨCA =
TCASE =
TLA =
PD =
Case-to-local ambient thermal characterization parameter (°C/W).
Processor case temperature (°C).
Local ambient temperature in chassis at processor (°C).
TDP dissipation (W) (assumes all power dissipates through the integrated heat
spreader (IHS)).
The case-to-local ambient thermal characterization parameter of the processor, ΨCA, is comprised of
ΨCS, the TIM thermal characterization parameter, and of ΨSA, the sink-to-local ambient thermal
characterization parameter:
ΨCA = ΨCS + ΨSA
16
Equation 4
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Where:
ΨCS = Thermal characterization parameter of the TIM (°C/W).
ΨSA = Thermal characterization parameter from heatsink-to-local ambient (°C/W).
ΨCS is strongly dependent on the thermal conductivity and thickness of the TIM between the
heatsink and IHS.
ΨSA is a measure of the thermal characterization parameter from the bottom of the heatsink to the
local ambient air. ΨSA is dependent on the heatsink material, thermal conductivity, and geometry. It
is also strongly dependent on the air velocity through the fins of the heatsink and the local ambient
temperature surrounding the heatsink.
Figure 2-7 illustrates the combination of the different thermal characterization parameters.
Figure 2-7. Processor Thermal Characterization Parameter Relationships
TLA
Ψ SA
HEATSINK
TS
TIM
PROCESSOR
TCASE
C
IHS
ΨCA
Ψ CS
SOCKET
Example
The cooling performance, ΨCA, is then defined using the principle of thermal characterization
parameter described above:
•
Define a target case temperature TCASE-MAX and corresponding TDP at a target frequency, F,
given in the processor datasheet.
•
Define a target local ambient temperature at the processor, TLA.
Since the processor thermal specifications (TCASE-MAX and TDP) can vary with the processor
frequency, it may be important to identify the worse case (lowest ΨCA) for a targeted chassis
(characterized by TLA) to establish a design strategy such that a given heatsink can cover a given
range of processor frequencies.
The following provides an illustration of how one might determine the appropriate performance
targets. The example power and temperature numbers used here are not related to any Intel
processor thermal specifications, and are for illustrative purposes only.
Assume the datasheet TDP is 85 W and the case temperature specification is 68 °C for a given
frequency. Assume as well that the system airflow has been designed such that the local processor
ambient temperature is 45°C. The following could be calculated using equation 1 from above for the
given frequency:
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ΨCA = (TCASE – TLA) / TDP = (68 – 45) / 85 = 0.27 °C/W
To determine the required heatsink performance, a heatsink solution provider would need to
determine ΨCS performance for the selected TIM and mechanical load configuration. If the heatsink
solution was designed to work with a TIM material performing at ΨCS ≤ 0.05 °C/W, solving for
equation 2 from above, the performance of the heatsink would be:
ΨSA = ΨCA − ΨCS = 0.27 − 0.05 = 0.22 °C/W
If the local processor ambient temperature is assumed to be 40°C, the same calculation can be
carried out to determine the new case-to-ambient thermal resistance:
ΨCA = (TCASE – TLA) / TDP = (68 – 40) / 85 = 0.33 °C/W
It is evident from the above calculations that, a reduction in the local processor ambient temperature
has a significant positive effect on the case-to-ambient thermal resistance requirement.
2.3.3
Chassis Thermal Design Considerations
2.3.3.1
Chassis Thermal Design Capabilities and Improvements
One of the critical parameters in thermal design is the local ambient temperature assumption of the
processor. Keeping the external chassis temperature fixed, internal chassis temperature rise is the
only component that can affect the processor local ambient temperature. Every degree gained at the
local ambient temperature directly translates into a degree relief in the processor case temperature.
Given the thermal targets for the processor, it is extremely important to optimize the chassis design
to minimize the air temperature rise upstream to the processor (TRISE), hence minimizing the
processor local ambient temperature. Please refer to Appendix B.
The heat generated by components within the chassis must be removed to provide an adequate
operating environment for both the processor and other system components. Moving air through the
chassis brings in air from the external ambient environment and transports the heat generated by the
processor and other system components out of the system. The number, size and relative position of
fans, vents and other heat generating components determine the chassis thermal performance, and
the resulting ambient temperature around the processor. The size and type (passive or active) of the
thermal solution and the amount of system airflow can be traded off against each other to meet
specific system design constraints. Additional constraints are board layout, spacing, component
placement, and structural considerations that limit the thermal solution size.
In addition to passive heatsinks, fan heatsinks and system fans, other solutions exist for cooling
integrated circuit devices. For example, ducted blowers, heat pipes and liquid cooling are all capable
of dissipating additional heat. Due to their varying attributes, each of these solutions may be
appropriate for a particular system implementation.
To develop a reliable, cost-effective thermal solution, thermal characterization and simulation
should be carried out at the entire system level, accounting for the thermal requirements of each
component. In addition, acoustic noise constraints may limit the size, number, placement, and types
of fans that can be used in a particular design.
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2.4
Thermal/Mechanical Reference Design
Considerations
2.4.1
Heatsink Solutions
2.4.1.1
Heatsink Design Considerations
To remove the heat from the processor, three basic parameters should be considered:
•
The area of the surface on which the heat transfer takes place - Without any
enhancements, this is the surface of the processor package IHS. One method used to improve
thermal performance is by attaching a heatsink to the IHS. A heatsink can increase the
effective heat transfer surface area by conducting heat out of the IHS and into the
surrounding air through fins attached to the heatsink base.
•
The conduction path from the heat source to the heatsink fins - Providing a direct
conduction path from the heat source to the heatsink fins and selecting materials with higher
thermal conductivity typically improves heatsink performance. The length, thickness, and
conductivity of the conduction path from the heat source to the fins directly impact the
thermal performance of the heatsink. In particular, the quality of the contact between the
package IHS and the heatsink base has a higher impact on the overall thermal solution
performance as processor cooling requirements become strict. Thermal interface material
(TIM) is used to fill in the gap between the IHS and the bottom surface of the heatsink, and
thereby improves the overall performance of the thermal stackup (IHS-TIM-Heatsink). With
extremely poor heatsink interface flatness or roughness, TIM may not adequately fill the gap.
The TIM thermal performance depends on its thermal conductivity as well as the pressure
load applied to it. Refer to Section 2.4.2 for further information on the TIM between the IHS
and the heatsink base.
•
The heat transfer conditions on the surface on which heat transfer takes place Convective heat transfer occurs between the airflow and the surface exposed to the flow. It is
characterized by the local ambient temperature of the air, TLA, and the local air velocity over
the surface. The higher the air velocity over the surface, the resulting cooling is more
efficient. The nature of the airflow can also enhance heat transfer via convection. Turbulent
flow can provide improvement over laminar flow. In the case of a heatsink, the surface
exposed to the flow includes the fin faces and the heatsink base.
An active heatsink typically incorporates a fan that helps manage the airflow through the heatsink.
Passive heatsink solutions require in-depth knowledge of the airflow in the chassis. Typically,
passive heatsinks see slower air speed. Therefore these heatsinks are typically larger (and heavier)
than active heatsinks due to the increase in fin surface required to meet a required performance. As
the heatsink fin density (the number of fins in a given cross-section) increases, the resistance to the
airflow increases: it is more likely that the air will travel around the heatsink instead of through it,
unless air bypass is carefully managed. Using air-ducting techniques to manage bypass area is an
effective method for maximizing airflow through the heat sink fins.
2.4.2
Thermal Interface Material
TIM application between the processor IHS and the heatsink base is generally required to improve
thermal conduction from the IHS to the heatsink. Many thermal interface materials can be preapplied to the heatsink base prior to shipment from the heatsink supplier and allow direct heatsink
attach, without the need for a separate TIM dispense or attach process in the final assembly factory.
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All thermal interface materials should be sized and positioned on the heatsink base in a way that
ensures the entire processor IHS area is covered. It is important to compensate for heatsink-toprocessor attach positional alignment when selecting the proper TIM size.
When pre-applied material is used, it is recommended to have a protective application tape over it.
This tape must be removed prior to heatsink installation.
The TIM performance is susceptible to degradation (i.e. grease breakdown) during the useful life of
the processor due to the temperature cycling phenomena. For this reason, the measured TCASE value
of a given processor can decrease over time depending on the type of TIM material.
2.4.3
Summary
In summary, considerations in heatsink design include:
2.4.4
•
The local ambient temperature TLA at the heatsink, airflow (CFM), the power being
dissipated by the processor, and the corresponding maximum TCASE. These parameters are
usually combined in a single lump cooling performance parameter, ΨCA (case to air thermal
characterization parameter). More information on the definition and the use of ΨCA is given
in Section 1.4 and Section 2.3.2.
•
Heatsink interface (to IHS) surface characteristics, including flatness and roughness.
•
The performance of the TIM used between the heatsink and the IHS.
•
Surface area of the heatsink.
•
Heatsink material and technology.
•
Development of airflow entering and within the heatsink area.
•
Physical volumetric constraints placed by the system.
Assembly Overview of the Intel Reference Thermal
Mechanical Design
The 2U+ cooling solution consists of the following components:
2.4.4.1
•
Heatsink (with captive standoff and screws)
•
Thermal Interface Material (TIM-2)
•
Hat Spring
Geometric Envelope
The baseboard keepout zones on the primary and secondary sides and height restrictions under the
enabling component region are shown in detail in Appendix A. The overall volumetric keep in zone
encapsulates the processor, socket, and the entire thermal/mechanical enabling solution.
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2.4.4.2
Assembly Drawing
Figure 2-8. Exploded View of Cooling Solution Thermal Solution Components
2.4.5
Thermal Solution Performance Characteristics
The optimization of the cooling solution heatsink for thermal performance is completed and Figure
2-9 shows the thermal performance and the pressure drop through fins of the heatsink versus the
airflow provided. The best-fit equations for these curves are also provided to make it easier for users
to determine the desired value without any error associated with reading the graph.
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Figure 2-9. 2U+ Cooling Solution Heatsink Thermal Performance
0.55
0.80
0.50
0.70
2
0.60
0.40
0.50
0.35
0.40
0.30
0.30
0.25
0.20
Mean Test Ψca = 0.2199 + 1.4415*CFM-1.0496
σ = 0.0086 C/W, non-uniform heat
0.20
0.15
0
10
20
30
40
50
60
70
80
90
∆P, inch water
Ψca, C/W
∆P Test = 5.47e-05CFM + 5.26e-03CFM
0.45
0.10
0.00
100
CFM Through Fins
If other custom heatsinks are intended for use with the 64-bit Intel Xeon processor MP with 1 MB
L2 cache, they must support the following interface control requirements to be compatible with the
reference mechanical components:
•
Requirement 1: Heatsink assembly must stay within the volumetric keep-in.
•
Requirement 2: Maximum mass and center of gravity:
Current maximum heatsink mass is 1000 grams [2.2 lbs] and the maximum center of gravity 3.81
cm [1.5 in.] above the bottom of the heatsink base.
•
Requirement 3: Maximum and minimum compressive load:
Any custom thermal solution design should meet the loading specification as documented within
this document, and should refer to the datasheet for specific details on package loading
specifications.
2.4.6
Structural Considerations of Cooling Solution
As Intel explores methods of keeping thermal solutions within the air-cooling space, the mass of the
thermal solutions is increasing. Due to the flexible nature (and associated large deformation) of
baseboard-only attachments, Intel reference solutions, such as cooling solution, are now commonly
using direct chassis attach (DCA) as the mechanical retention design. The mass of the new thermal
solutions is large enough to require consideration for structural support and stiffening on the chassis.
Intel has published a best know method (BKM) document that provides specific structural guidance
for designing DCA thermal solutions. The document is titled Chassis Strength and Stiffness
Measurement and Improvement Guidelines for Direct Chassis Attach Solutions.
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2.4.7
Components Overview
2.4.7.1
Heatsink with Captive Screws and Standoffs
The cooling solution reference heatsink uses snapped-fin technology for its design. It consists of a
copper base and copper fins with Shin-Etsu* G751 thermal grease as the TIM. The mounting screws
and standoffs are also made captive to the heatsink base for ease of handling and assembly as shown
in Figure 2-10.
Figure 2-10. Isometric View of the 2U+ Cooling Solution Heatsink
NOTE:
Refer to Appendix A for more detailed mechanical drawings of the heatsink.
The function of the standoffs is to provide a bridge between the chassis and the heatsink for
attaching and load carrying. When assembled, the heatsink is rigid against the top of the standoff,
and the standoff is rigid to a chassis standoff with the hat spring firmly sandwiched between the
two. In dynamic loading situations the standoffs carry much of the heatsink load, especially in
lateral conditions, when compared to the amount of load transmitted to the processor package. As
such, it is comprised of steel. The distance from the bottom of the heatsink to the bottom of the
standoff is 1.02 cm [0.402 in.].
The function of the screw is to provide a rigid attach method to sandwich the entire cooing solution
assembly together, activating the hat spring under the baseboard, and thus providing the TIM
preload. A screw is an inexpensive, low profile solution that does not negatively impact the thermal
performance of the heatsink due to air blockage. Any fastener (i.e. head configuration) can be used
as long as it is of steel construction; the head does not interfere with the heatsink fins, and is of the
correct length of 1.27 cm [0.50 in.].
Although the cooling solution heatsink fits into the legacy volumetric keep-in, it has a larger
footprint due to the elimination of retention mechanism and clips used in the older enabled
thermal/mechanical components. This allows the heatsink to grow its base and fin dimensions,
further improving the thermal performance. A drawback of this enlarged size and use of copper for
both the base and fins is the increased weight of the heatsink. The cooling solution heatsink is
estimated to weigh twice as much as previous heatsinks used with Intel Xeon processors. However,
the retention scheme employed by cooling solution is designed to support heavy heatsinks
(approximately up to 1000 grams) in cases of shock, vibration and installation as explained in
Appendix D.
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2.4.7.2
Thermal Interface Material (TIM-2)
A TIM must be applied between the package and the heatsink to ensure thermal conduction. The
cooling solution reference design uses Shin-Etsu* G751 thermal grease.
The recommended grease dispenses weight to ensure full coverage of the processor IHS is given
below. For an alternate TIM, full coverage of the entire processor IHS is recommended.
Table 2-4. Recommended Thermal Grease Dispense Weight
Processor
®
64-bit Intel Xeon™
Processor MP with
1 MB L2 Cache
Recommended
Thermal Grease
Dispense Weight
(mg)
Shin-Etsu* G751
400
It is recommended that you use thermally conductive grease as the TIM requires special handling
and dispense guidelines. The following guidelines apply to Shin-Etsu G751 thermal grease. The use
of a semi-automatic dispensing system is recommended for high volume assembly to ensure an
accurate amount of grease is dispensed on top of the IHS prior to assembly of the heatsink. A typical
dispense system consists of an air pressure and timing controller, a hand held output dispenser, and
an actuation foot switch. Thermal grease in cartridge form is required for dispense system
compatibility. A precision scale with an accuracy of ±5 mg is recommended to measure the correct
dispense weight and set the corresponding air pressure and duration. The IHS surface should be free
of foreign materials prior to grease dispense
Additional recommendations include recalibrating the dispense controller settings after any two
hour pause in grease dispense. The grease should be dispensed just prior to heatsink assembly to
prevent any degradation in material performance. Finally, the thermal grease should be verified to
be within its recommended shelf life before use.
The cooling solution reference solution is designed to apply a compressive load of up to 222 N [50
lbf] on the TIM to improve the thermal performance.
2.4.7.3
Hat Spring
The hat spring, which is attached on the secondary side of the baseboard, is made from 0.80 mm
[0.0315 in.] thick 301 stainless steel half hard. Any future versions of the spring will be made from a
similar material. The hat spring has four embosses (called “hats”) which, when assembled, rest on
the top of the chassis standoffs. The hat spring is located between the chassis standoffs and the
heatsink standoffs. The purpose of the hat spring is to provide compressive preload at the TIM
interface when the baseboard is pushed down upon it. This spring does not function as a clip of any
kind. The two tabs on the spring are used to provide the necessary compressive preload for the TIM
when the whole solution is assembled. The tabs make contact on the secondary side of the
baseboard. In order to avoid damage to the contact locations on the baseboard, the tabs will be
insulated with a 0.127 mm [0.005 in.] thick Kapton* tape (or equivalent). Figure 2-11 shows an
isometric view of the hat spring design.
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Figure 2-11. Hat Spring Isometric View
Figure 2-12. Isometric View of Hat Spring Attachment to the Base Board
Secondary
Primary
Primary
Secondary
Please refer to Appendix A for more detailed mechanical drawings of the hat spring. Also, the
baseboard keepout requirements shown in Appendix A must be met to use this hat spring design.
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A
Mechanical Drawings
The mechanical drawings included in this appendix. These drawings refer to the thermal mechanical
enabling components for the 64-bit Intel Xeon processor MP with 1 MB L2 cache.
Note: Intel reserves the right to make changes and modifications to the design as necessary.
Table A-1. Mechanical Drawing List
Drawing Description
Figure Number
2U Cooling Solution Heatsink (Sheet 1 of 4)
Figure A-1
2U Cooling Solution Heatsink (Sheet 2 of 4)
Figure A-2
2U Cooling Solution Heatsink (Sheet 3 of 4)
Figure A-3
2U Cooling Solution Heatsink (Sheet 4 of 4)
Figure A-4
Cooling Solution Hat Spring (Sheet 1 of 3)
Figure A-5
Cooling Solution Hat Spring (Sheet 2 of 3)
Figure A-6
Cooling Solution Hat Spring (Sheet 3 of 3)
Figure A-7
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 1 of 5)
Figure A-8
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 2 of 5)
Figure A-9
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 3 of 5)
Figure A-10
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 4 of 5)
Figure A-11
Baseboard Keepout Footprint Definition and Height Restrictions for
Enabling Components (Sheet 5 of 5)
Figure A-12
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Figure A-1. 2U Cooling Solution Heatsink (Sheet 1 of 4)
Figure A-2. 2U Cooling Solution Heatsink (Sheet 2 of 4)
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Figure A-3. 2U Cooling Solution Heatsink (Sheet 3 of 4)
Figure A-4. 2U Cooling Solution Heatsink (Sheet 4 of 4)
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Figure A-5. Cooling Solution Hat Spring (Sheet 1 of 3)
Figure A-6. Cooling Solution Hat Spring (Sheet 2 of 3)
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Figure A-7. Cooling Solution Hat Spring (Sheet 3 of 3)
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Figure A-8. Baseboard Keepout Footprint Definition and Height Restrictions for Enabling
Components (Sheet 1 of 5)
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Figure A-9. Baseboard Keepout Footprint Definition and Height Restrictions for Enabling
Components (Sheet 2 of 5)
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Figure A-10. Baseboard Keepout Footprint Definition and Height Restrictions for Enabling
Components (Sheet 3 of 5)
Figure A-11. Baseboard Keepout Footprint Definition and Height Restrictions for Enabling
Components (Sheet 4 of 5)
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Figure A-12. Baseboard Keepout Footprint Definition and Height Restrictions for Enabling
Components (Sheet 5 of 5)
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B
Testing Methods
B.1
Case Measurement
Processor cooling performance is determined by measuring the case temperature using a
thermocouple and then applying the corresponding correction offset to this measurement. For case
temperature measurements, the attach method outlined in this section is recommended for mounting
a thermocouple.
Special care is required when measuring case temperature (TC) to ensure an accurate temperature
measurement. Thermocouples are often used to measure TC. When measuring the temperature of a
surface that is at a different temperature from the surrounding local ambient air, errors could be
introduced in the measurements. The measurement errors could be caused by poor thermal contact
between the thermocouple junction and the surface of the integrated heat spreader, heat loss by
radiation, convection, by conduction through thermocouple leads, or by contact between the
thermocouple cement and the heatsink base. To minimize these measurement errors, the approach
outlined in the next section is recommended.
B.2
Supporting Test Equipment
To apply the reference thermocouple attach procedure, it is recommended to use the equipment (or
equivalent).
Table B-1. Test Equipment
Item
Description
Part Number
Measurement and Output
Microscope
Olympus* Light microscope or equivalent.
SZ-40
Digital Multi Meter
Digital Multi Meter for resistance measurement.
Not Available
Micromanipulator
(See Note below)
Micromanipulator set from YOU* Ltd. Or equivalent
Mechanical 3D arm with needle (not included) to maintain TC
bead location during the attach process.
Test Fixture(s)
YOU-3
Miscellaneous Hardware
Loctite* 498 Adhesive
Super glue w/thermal characteristics.
49850
Adhesive Accelerator
Loctite* 7452 for fast glue curing.
18490
Kapton* Tape
For holding thermocouple in place or equivalent.
Not Available
Thermocouple
Omega*, 36 gauge, "T" Type.
5SRTC-TT-36-72
Ice Point Cell
Omega*, stable 0 C temperature source for calibration and
offset.
TRCIII
Hot Point Cell
Omega*, temperature source to control and understand
meter slope gain.
CL950-A-110
Calibration and Control
NOTE:
Three axes set consists of (1ea. U-31CF), (1ea. UX-6-6), (1ea. USM6) and (1ea. UPN-1). More information available at:
http://www.narishige.co.jp/you_ltd/english/products/set/you-set.htm#3
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B.3
Thermal Calibration and Controls
It is recommended that full and routine calibration of temperature measurement equipment be
performed before attempting to perform temperature case measurement of processors. Intel
recommends checking the meter probe set against known standards. This should be done at 0 ºC
(using ice bath or other stable temperature source) and at an elevated temperature, around 80 ºC
(using an appropriate temperature source).
Wire gauge and length also should be considered as some less expensive measurement systems are
heavily impacted by impedance. There are numerous resources available throughout the industry to
assist with implementation of proper controls for thermal measurements.
B.4
1.
It is recommended to follow company standard procedures and wear safety items like glasses
for cutting the IHS and gloves for chemical handling.
2.
Ask your Intel field sales representative if you need assistance to groove and/or install a
thermocouple according to the reference process.
IHS Groove
Cut a groove in the package IHS according to the drawing.
Figure B-1. IHS Groove
NOTE:
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Figure B-2. Groove to Pin Indicator
When the processor is installed in the socket, the groove is perpendicular to the socket load lever,
and on the opposite side of the lever.
Figure B-3. IHS Groove
Select a machine shop that is capable of holding drawing specified tolerances. IHS channel
geometry is critical for repeatable placement of the thermocouple bead, ensuring precise thermal
measurements. The specified dimensions minimize the impact of the groove on the IHS under the
socket load. A larger groove may cause the IHS to warp under the socket load such that it does not
represent the performance of an ungrooved IHS on production packages.
Note: Inspect parts for compliance to specifications before accepting from machine shop.
B.5
Thermocouple Conditioning and Preparation
1.
Use a calibrated thermocouple.
2.
Measure the thermocouple resistance by holding both wires on one probe and the tip of
thermocouple to the other probe of the DMM (compare to thermocouple resistance
specifications).
3.
Straighten the wire for about 38 mm [1 inch] from the bead to place it inside the channel.
4.
Bend the tip of the thermocouple at approximately 45 degree angle by about 0.8 mm [0.030
inch] from the tip.
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Figure B-4. Bending Tip of Thermocouple
B.6
40
Thermocouple Attachment to the IHS
1.
Clean groove with IPA and a lint free cloth removing all residues prior to thermocouple
attachment.
2.
Place the thermocouple wire inside the groove letting the exposed wire and bead extend about
3.2 mm [0.125 inch] past the end of groove. Secure it with Kapton tape.
3.
Lift the wire at the middle of groove with tweezers and bend the front of wire to place the
thermocouple in the channel ensuring the tip is in contact with the end of the channel grooved
in the IHS.
4.
Place the processor under the microscope unit to continue with process. It is also
recommended to use a fixture (like processor tray or a plate) to help holding the unit in place
for the rest of the attach process.
5.
Press the wire down about 6mm [0.125"] from the thermocouple bead using the tweezers.
Look in the microscope to perform this task. Place a piece of Kapton tape to hold the wire
inside the groove.
6.
Using the micromanipulator, install the needle near to the end of groove on top of
thermocouple. Using the X, Y, and Z axes on the arm place the tip of needle on top of the
thermocouple bead. Press down until the bead is seated at the end of groove on top of the step.
7.
Measure resistance from thermocouple end wires (hold both wires to a DMM probe) to the
IHS surface. This should be the same value as measured during the thermocouple
conditioning.
8.
Place a small amount of Loctite 498 adhesive in the groove where the bead is installed. Using
a fine point device, spread the adhesive in the groove around the needle, the thermocouple
bead and the thermocouple wires already installed in the groove during step 5 above. Be
careful not to move the thermocouple bead during this step.
9.
Measure the resistance from the thermocouple end wires again using the DMM and to ensure
the bead is still properly contacting the IHS.
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Figure B-5. Securing Thermocouple Wires with Kapton* Tape
Figure B-6. Thermocouple Bead Placement
Figure B-7. Thermocouple Placement
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Figure B-8. 3D Micromanipulator to Secure Bead Location
Figure B-9. Measuring Resistance between Thermocouple and IHS
Figure B-10. Applying the Adhesive on the Thermocouple Bead
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B.7
Curing Process
1.
Let the thermocouple attach set in the open-air for at least 1/2 Hr. It is not recommended to
use any curing accelerator like Loctite* Accelerator 7452 for this step, as rapid contraction of
the adhesive during curing may weaken bead attach on the IHS.
2.
Reconfirm electrical connectivity with DMM before removing the micromanipulator.
3.
Remove the 3D Arm needle by holding down the processor unit and lifting the arm.
4.
Remove the Kapton* tape, straighten the wire in the groove so it lays flat all the way to the
end of the groove.
5.
Using a blade to shave excess adhesive above the IHS surface.
Take usual precautions when using open blades.
B.8
1.
Install new Kapton* tape to hold the thermocouple wire down and fill the rest of groove with
adhesive. Make sure the wire and insulation is entirely within the groove and below the IHS
surface.
2.
Curing time for the rest of the adhesive in the groove can be reduced using Loctite*
Accelerator 7452.
3.
Repeat step 5 to remove any access adhesive to ensure flat IHS for proper mechanical contact
to the heatsink surface.
Thermocouple Wire Management
Figure B-11. Thermocouple Wire Management in the Groove
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Figure B-12. Removing Excess Adhesive from the IHS
Figure B-13. Filling the Groove with Adhesive
When installing the processor into the socket, make sure that the thermocouple wires exit above the
load plate. Pinching the thermocouple wires between the load plate and the IHS will likely damage
the wires.
Note: When thermocouple wires are damaged, the resulting reading may likely be wrong. For example, if
there are any cuts into the wires insulation where the wires are pinched between the IHS and the
load plate, the thermocouple wires can get in contact at this location. In that case, the temperature
would be really measured will be measured on the edge of the IHS/socket load plate area. This
temperature will likely be much lower than the temperature at the center of the IHS.
Prior to installing the heatsink, make sure that the thermocouple wires remain below the IHS top
surface, by running a flat blade on top of the IHS for example.
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Figure B-14. Thermocouple Wire Management
B.9
Local Air Thermocouple Placement
For passive heatsinks, two thermocouples will be placed 10 mm upstream of the processor heatsink.
The thermocouples will be centered with respect to the height of the heatsink fins and evenly across
the width of the heatsink.
For active heatsinks, four thermocouples will be placed on the fan inlet. These thermocouples will
be mounted between 5 mm and 10 mm above the fan. The average of these measurements will be
used to represent the local inlet temperature to the active heatsink.
Figure B-15. Local Air Thermocouple Placement for Passive Heatsinks
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Figure B-16. Local Air Thermocouple Placement for Active Heatsinks (Side View)
Figure B-17. Local Air Thermocouple Placement for Active Heatsinks (Plan View)
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C
Safety Requirements
Heatsink and attachment assemblies shall be consistent with the manufacture of units that meet the
safety standards:
•
UL Recognition-approved for flammability at the system level. All mechanical and thermal
enabling components must be a minimum UL94V-2 approved.
•
CSA Certification. All mechanical and thermal enabling components must have CSA
certification.
•
Heatsink fins must meet the test requirements of UL1439 for sharp edges.
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D
Quality and Reliability
Requirements
D.1
Intel Verification Criteria for the Reference Designs
D.1.1
Reference Heatsink Thermal Verification
The Intel reference heatsinks will be verified within specific boundary conditions based on the
methodology described in Appendix B.
The test results, for a number of samples, are reported in terms of a worst-case mean + 3σ value for
thermal characterization parameter using real processors.
D.1.2
Environmental Reliability Testing
D.1.2.1
Structural Reliability Testing
Structural reliability tests consist of unpackaged, board-level vibration and shock tests of a given
thermal solution in assembled state, as well as long-term reliability testing (temperature cycling,
bake test). The thermal solution should be capable of sustaining thermal performance after these
tests are conducted; however, the conditions of the tests outlined here may differ from the
customers’ system requirements.
D.1.2.2
Random Vibration Test Procedure
•
Duration: 10 min/axis, 3 axes
•
Frequency Range: 5 Hz to 500 Hz
•
Power Spectral Density (PSD) Profile: 3.13 G RMS (refer to Figure D-1).
Figure D-1. Random Vibration PSD
0.1
3.13 GRMS (10 Minutes Per Axis)
PSD (g^2/Hz)
(20, 0.02)
(500, 0.02)
(5, 0.01)
0.01
5 Hz
500 Hz
0.001
1
10
100
1000
Frequency (Hz)
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D.1.2.3
Shock Test Procedure
Recommended performance requirement for a baseboard:
•
Quantity: 3 drops for + and – directions in each of 3 perpendicular axes (i.e. total 18 drops).
•
Profile: 50 G trapezoidal waveform, 11 ms duration, 4.32 m/sec minimum velocity change.
•
Setup: Mount sample board on test fixture.
Figure D-2. Shock Acceleration Curve
60
Accelration (g)
50
40
30
20
10
0
0
2
4
6
8
10
12
Time (Milliseconds)
D.1.2.4
Recommended Test Sequence
Each test sequence should start with components (i.e. baseboard, heatsink assembly, etc.) that have
not been previously submitted to any reliability testing.
The test sequence should always start with a visual inspection after assembly, and
BIOS/Processor/memory test. The stress test should be then followed by a visual inspection and
then BIOS/Processor/memory test.
D.1.2.5
Post-Test Pass Criteria
The post-test pass criteria are:
50
1.
No significant physical damage to the heatsink and retention hardware.
2.
Heatsink remains seated and its bottom remains mated flatly against the IHS surface. No
visible gap between the heatsink base and processor IHS. No visible tilt of the heatsink with
respect to the retention hardware.
3.
No signs of physical damage on baseboard surface due to impact of heatsink.
4.
No visible physical damage to the processor package.
5.
Successful BIOS/Processor/memory test of post-test samples.
6.
Thermal compliance testing to demonstrate that the case temperature specification can be met.
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D.1.2.6
Recommended BIOS/Processor/Memory Test Procedures
This test is to ensure proper operation of the product before and after environmental stresses, with
the thermal mechanical enabling components assembled. The test shall be conducted on a fully
operational baseboard that has not been exposed to any battery of tests prior to the test being
considered.
Testing setup should include the following components, properly assembled and/or connected:
•
Appropriate system baseboard.
•
Processor and memory.
•
All enabling components, including socket and thermal solution parts.
The pass criterion is that the system under test shall successfully complete the checking of BIOS,
basic processor functions and memory, without any errors. Intel PC Diags is an example of software
that can be utilized for this test.
D.1.3
Material and Recycling Requirements
Material shall be resistant to fungal growth. Examples of non-resistant materials include cellulose
materials, animal and vegetable based adhesives, grease, oils, and many hydrocarbons. Synthetic
materials such as PVC formulations, certain polyurethane compositions (e.g. polyester and some
polyethers), plastics which contain organic fillers of laminating materials, paints, and varnishes also
are susceptible to fungal growth. If materials are not fungal growth resistant, then MIL-STD-810E,
Method 508.4 must be performed to determine material performance.
Material used shall not have deformation or degradation in a temperature life test.
Any plastic component exceeding 25 grams must be recyclable per the European Blue Angel
recycling standards.
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E
Enabled Suppliers Information
Component
Cooling Solution
Heatsink
Development
Suppliers
Description
Copper Fin, Copper
Base
Fujikura* (stacked fin)
CNDA 36187
Furukawa (crimped fin)
CNDA 65755
Supplier Contact Info
Mechatronics*
Steve Carlson
800-453-4569 x205
steve@mechatronics.com
Furukawa America
Katsu Mizushima
(408) 232-9306
katsumizushima@mindspring.com
Thermal Interface
Material
Grease
Shin-Etsu* G751
CNDA 75610
Donna Hartigan
(480) 893-8898
Cooling Solution
Spring
Stainless Steel 301,
Kapton* Tape on
Spring Fingers
ITW Fastex*
CNDA 78538
Ron Schmidt
(847) 299-2222
rschmidt@itwfastex.com
Felicia Lee
886-2-22996390 x144
felicia@avc.com.tw
AVC*
CNDA 2085011
Foxconn*
CNDA 11251
§
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F
Processor Thermal Management
Logic and Thermal Monitor
Features
F.1
Thermal Management Logic and Thermal Monitor
Feature
F.1.1
Processor Power Dissipation
An increase in processor operating frequency not only increases system performance, but also
increases the processor power dissipation. The relationship between frequency and power is
generalized in the following equation: P = CV2F (where P = power, C = capacitance, V = voltage,
F = frequency). From this equation, it is evident that power increases linearly with frequency and
with the square of voltage. In the absence of power saving technologies, ever increasing frequencies
will result in processors with power dissipations in the hundreds of watts. Fortunately, there are
numerous ways to reduce the power consumption of a processor, and Intel is aggressively pursuing
low power design techniques. For example, decreasing the operating voltage, reducing unnecessary
transistor activity, and using more power efficient circuits can significantly reduce processor power
consumption.
An on-die thermal management feature called Thermal Monitor is available on the 64-bit Intel Xeon
processor MP with 1 MB L2 cache. It provides a thermal management approach to support the
continued increases in processor frequency and performance. By using a highly accurate on-die
temperature sensing circuit and a fast acting temperature control circuit, the processor can rapidly
initiate thermal management control. The Thermal Monitor can reduce cooling solution cost, by
allowing designs to target TDP instead of maximum processor power.
F.1.2
Thermal Monitor Implementation
On the 64-bit Intel Xeon processor MP with 1 MB L2 cache, the Thermal Monitor is integrated into
the processor silicon. The Thermal Monitor includes:
•
An on-die temperature sensing circuit.
•
An external output signal (PROCHOT#) that indicates the processor has reached its
maximum operating temperature.
•
An external input signal (FORCEPR#) that allows the platform to force a power reduction by
the processor by activating the TCC.
•
A TCC that can reduce processor temperature by rapidly reducing power consumption when
the on-die temperature sensor indicates that it has reached the maximum operating point.
•
Registers to determine the processor thermal status.
The processor temperature is determined through an analog thermal sensor circuit comprised of a
temperature sensing diode, a factory calibrated reference current source, and a current comparator
(see Figure F-1). A voltage applied across the diode induces a current flow that varies with
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temperature. By comparing this current with the reference current, the processor temperature can be
determined. The reference current source corresponds to the diode current when at the maximum
permissible processor operating temperature. Processors are calibrated during manufacturing on a
small sample set. Once configured, the processor temperature at which the PROCHOT# signal is
asserted (trip point) is not re-configurable.
Figure F-1. Thermal Sensor Circuit
Temperature Sensing Diode
Current Comparator
PROCHOT#
Reference Current Source
The PROCHOT# signal is available internally to the processor as well as externally. External
indication of the processor temperature status is provided through the bus signal PROCHOT#.
When the processor temperature reaches the trip point, PROCHOT# is asserted. When the processor
temperature is below the trip point, PROCHOT# is de-asserted. Assertion of the PROCHOT# signal
is independent of any register settings within the processor. It is asserted any time the processor die
temperature reaches the trip point. The point where the TCC activates is set to the same temperature
at which the processor is tested and at which PROCHOT# asserts.
The TCC portion of the Thermal Monitor must be enabled for the processor to operate within
specifications. The Thermal Monitor’s TCC, when active, lowers the processor temperature by
reducing the power consumed by the processor. This is done by changing the duty cycle of the
internal processor clocks, resulting in a lower effective frequency. When active, the TCC turns the
processor clocks off and then back on with a predetermined duty cycle. The duty cycle is processor
specific, and is fixed for a particular processor. The maximum time period the clocks are disabled is
~3 µs, and is frequency dependent. Higher frequency processors will disable the internal clocks for a
shorter time period. Figure F-2 illustrates the relationship between the internal processor clocks and
PROCHOT#.
Performance counter registers, status bits in model specific registers (MSRs), and the PROCHOT#
output pin are available to monitor and control the Thermal Monitor behavior.
Figure F-2. Concept for Clocks under Thermal Monitor Control
PROCHOT#
Normal clock
Core clock w/
TM2 Engaged
VID w/ TM2
Engaged
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F.1.3
Operation and Configuration
To maintain compatibility with previous generations of processors, which have no integrated
thermal logic, the TCC portion of Thermal Monitor is disabled by default. During the boot process,
the BIOS must enable the TCC; or a software driver may do this after the operating system has
booted. Thermal Monitor or Thermal Monitor 2 feature must be enabled for the processor to
remain within specification.
The TCC feature can be configured and monitored in a number of ways. OEMs are expected to
enable the TCC while using various registers and outputs to monitor the processor thermal status.
The TCC is enabled by the BIOS setting a bit in an MSR (model specific register). Enabling the
TCC allows the processor to maintain a safe operating temperature without the need for special
software drivers or interrupt handling routines. When the TCC has been enabled, processor power
consumption will be reduced within a few hundred clock cycles after the thermal sensor detects a
high temperature, i.e. PROCHOT# assertion. The TCC and PROCHOT# transition to inactive once
the temperature has been reduced below the thermal trip point, although a small time-based
hysteresis has been included to prevent multiple PROCHOT# transitions around the trip point.
External hardware can monitor PROCHOT# and generate an interrupt whenever there is a transition
from active-to-inactive or inactive-to-active. PROCHOT# can also be configured to generate an
internal interrupt which would initiate an OEM supplied interrupt service routine. Regardless of the
configuration selected, PROCHOT# will consistently indicate the thermal status of the processor.
The TCC can also be activated manually using an “on-demand” mode.
F.1.4
Thermal Monitor 2
The 64-bit Intel Xeon processor MP with 1 MB L2 cache also supports an enhanced TCC that works
in conjunction with the existing Thermal Monitor logic. This capability is known as Thermal
Monitor 2. This improved TCC provides a more efficient means for limiting the processor
temperature by reducing the power consumption within the processor.
When Thermal Monitor 2 is enabled, and a high temperature situation is detected, the enhanced
TCC will be activated. The enhanced TCC causes the processor to adjust its operating frequency
(bus-to-core multiplier) and input voltage identification (VID) value. This combination of reduced
frequency and the lowering of VID results in a reduction in processor power consumption.
A processor enabled for Thermal Monitor 2 includes two operating points, each consisting of a
specific operating frequency and voltage. The first operating point represents the normal operating
condition for the processor. The second operating point consists of both a lower operating frequency
and voltage.
When the TCC is activated, the processor automatically transitions to the new frequency. This
transition occurs very rapidly (on the order of 5 microseconds). During the frequency transition, the
processor is unable to service any bus requests, and consequently, all bus traffic is blocked during
the frequency transition. Edge-triggered interrupts will be latched and kept pending until the
processor resumes operation at the new frequency.
Once the new operating frequency is engaged, the processor will transition to the new core operating
voltage by issuing a new VID code to the voltage regulator. The voltage regulator must support
dynamic VID changes in order to support Thermal Monitor 2. During the voltage change, it will be
necessary to transition through multiple VID codes to reach the target operating voltage. Each step
will be one VID table entry (i.e. 12.5 mV steps). The processor continues to execute instructions
during the voltage transition. Operation at the lower voltage reduces both the dynamic and leakage
power consumption of the processor. Once the processor has sufficiently cooled, and the time based
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hysteresis period has expired, the operating frequency and voltage transition back to the normal
system operating point. Transition of the VID code will occur first, in order to insure proper
operation once the processor reaches its normal operating frequency. Refer to Figure F-3 for an
illustration of this ordering.
Figure F-3. Thermal Monitor 2 Frequency and Voltage Ordering
TTM2
Temperature
fMAX
fTM2
Frequency
VNOM
VTM2
Vcc
Time
T(hysterisis)
F.1.5
System Considerations
The Thermal Monitor feature may be used in a variety of ways, depending upon the system design
requirements and capabilities.
Note: Intel requires the TCC to be enabled for all 64-bit Intel Xeon processor MP with 1 MB L2
cache -based systems. At a minimum, the TCC provides an added level of protection against
processor thermal solution failure.
A system designed to meet the TDP and TCASE targets published in the processor datasheet greatly
reduces the probability of real applications causing the TCC to activate under normal operating
conditions. Systems that do not meet these specifications could be subject to more frequent
activation of the TCC depending upon ambient air temperature and application power profile.
Moreover, if a system is significantly under designed, there is a risk that the Thermal Monitor
feature will not be capable of maintaining a safe operating temperature and the processor could
shutdown and signal THERMTRIP#.
For information regarding THERMTRIP#, refer to Appendix F.1.7.2 and to the processor datasheet
F.1.6
Operating System and Application Software Considerations
The Thermal Monitor feature and its TCC work seamlessly with ACPI compliant operating systems
and those utilizing hardware based timing routines. The Thermal Monitor feature is transparent to
application software since the processor bus snooping, ACPI timer, and interrupts are active at all
times.
Activation of the TCC during a non-ACPI aware operating system boot process may result in
incorrect calibration of operating system software timing loops. This is also the case with operating
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systems that utilize execution based timing routines. The BIOS must disable the TCC prior to boot
and then the operating system or BIOS must enable the TCC after the operating system boot process
completes.
Intel has worked with the major operating system vendors to ensure support for non-execution based
operating system calibration loops and ACPI support for the Thermal Monitor feature.
F.1.7
Legacy Thermal Management Capabilities
In addition to Thermal Monitor, the 64-bit Intel Xeon processor MP with 1 MB L2 cache supports
the same thermal management features originally introduced with the Intel® Pentium® III Xeon™
processor. These features include the on-die thermal diode and THERMTRIP# signal for indicating
catastrophic thermal failure.
F.1.7.1
On-Die Thermal Diode
There are two independent thermal diodes in the 64-bit Intel Xeon processor MP with 1 MB L2
cache. One is the on-die thermal diode and the other is in the temperature sensor used for the
Thermal Monitor and for THERMTRIP#. The Thermal Monitor’s temperature sensor and the on-die
thermal diode are independent and isolated devices with no direct correlation to one another. Circuit
constraints and performance requirements prevent the Thermal Monitor’s temperature sensor and
the on-die thermal diode from being located at the same place on the silicon. The temperature
distribution across the die may result in significant temperature differences between the on-die
thermal diode and the Thermal Monitor’s temperature sensor. This temperature variability across the
die is highly dependent on the application being run. As a result, it is not possible to predict the
activation of the TCC by monitoring the on-die thermal diode.
System integrators that plan on using the thermal diode for system or component level fan control
need to be aware of the potential for rapid changes in processor power consumption as the executing
workload changes. Variable performance thermal solutions that fail to react quickly to changing
workloads may experience TCC activation or worst yet, result in automatic shutdown via
THERMTRIP# (refer to Appendix F.1.7.2 for more information on THERMTRIP). One example of
this situation is as follows: A fan control scheme slows the fans such that the processor is operating
very near the thermal trip point while executing a relatively low power workload. The start of a
higher power application creates a sudden increase in power consumption and elevates the
temperature of the processor above the trip point, causing the TCC to activate. The power reduction
resulting from TCC activation slows the rate of temperature increase, but is not sufficient to clamp
the temperature, due to inadequate thermal solution performance at reduced fan speed. As a result,
the temperature continues to slowly increase. The fan is then sped up to compensate for the change
in processor workload but reacts too slowly to prevent the processor from shutting down due to
THERMTRIP# activation.
High temperature change rates on-die can also limit the ability to accurately measure the on-die
thermal diode temperature. As a result, the on-die thermal diode should not be relied upon to warn
of processor cooling system failure or predict the onset of the TCC. An illustration of this is as
follows. Many thermal diode sensors report temperatures a maximum of 8 times per second. Within
the 1/8th (0.125 sec.) second time period, the temperature is averaged over 1/16th of a second. In a
scenario where the silicon temperature ramps at 50°C/sec, or approximately 6°C/0.125 sec, the
processor will be ~4.5°C above the temperature reported by the thermal sensor. Change in diode
temperature averaged over 1/16th seconds = ~1.5°C; temperature reported 1/16th second later at 1/8th
second when the actual processor temperature would be 6°C higher (see Figure F-4).
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The on-die thermal diode can be used with an external device (thermal diode sensor) to monitor
long-term temperature trends. By averaging this data information over long time periods (hours/days
vs. min/sec), it may be possible to derive a trend of the processor temperature. Analysis of this
information could be useful in detecting changes in the system environment that may require
attention. Design characteristics and usage models of the thermal diode sensors are described in
datasheets available from the thermal diode sensor manufacturers.
Figure F-4. On-Die Thermal Diode Sensor Time Delay
Processor Temperature
Temperature is Averaged over
1/16th Second
Temperature is
Reported 1/16th
Second Later
Processor
Temperature Ramp
Time in 1/16th Second Intervals
F.1.7.2
THERMTRIP# Signal Pin
In the event of a catastrophic cooling failure, the processor will automatically shut down when the
silicon temperature has reached its operating limit. At this point the system bus signal
THERMTRIP# signal goes active and power must be removed from the processor. THERMTRIP#
stays active until RESET# has been initiated. THERMTRIP# activation is independent of processor
activity and does not generate any bus cycles.
F.1.7.3
FORCEPR# Signal Pin
The 64-bit Intel Xeon processor MP with 1 MB L2 cache provides a means for system hardware to
force activation of the TCC. One possible usage model would be to use this capability to protect the
voltage regulator from overheating in order to avoid a catastrophic shutdown. Refer to the
appropriate platform design guidelines and voltage regulator design guidelines for implementation
details. The use of the FORCEPR# signal pin requires that BIOS code enable the signal’s
recognition via an MSR.
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F.1.8
Cooling System Failure Warning
If desired, the system may be designed to cool the maximum processor power. In this situation, it
may be useful to use the PROCHOT# signal as an indication of cooling system failure. Messages
could be sent to the system administrator to warn of the cooling failure, while the TCC would allow
the system to continue functioning or allow a graceful system shutdown. If no thermal management
action is taken, the silicon temperature may exceed the operating limits, causing THERMTRIP# to
activate and shut down the processor. Regardless of the system design requirements or thermal
solution ability, the Thermal Monitor feature must still be enabled to ensure proper processor
operation.
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