Intel 845PE Guide

Intel®845PE/845GE Chipset
Thermal Design Guide
Intel®82845GE GMCH / Intel®82845PE MCH Thermal and
Mechanical Design Guidelines
September 2006
Document Number: 251926-002
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2 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH INTEL®PRODUCTS. NO LICENSE, EXPRESS OR IMPLIED, BY
ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. EXCEPT AS PROVIDED IN
INTEL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, INTEL ASSUMES NO LIABILITY WHATSOEVER, AND INTEL DISCLAIMS
ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO SALE AND/OR USE OF INTEL PRODUCTS INCLUDING LIABILITY OR WARRANTIES
RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR
OTHER INTELLECTUAL PROPERTY RIGHT. Intel products are not intended for use in medical, life saving, or life sustaining applications.
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 responsibilitywhatsoever for conflicts or incompatibilities arising from future changes to them.
The Intel®82845GE GMCH / Intel®82845PE MCH chipset may contain design defects or errors known as errata which may cause the product to
deviate from published specifications. Current characterized errata are available on request.
Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.
Intel, Pentium, and the Intel logo are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other
countries.
*Other names and brands may be claimed as the property of others.
Copyright © 2002, Intel Corporation

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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 3
Contents
1Introduction.....................................................................................................................7
1.1 Definition of Terms.............................................................................................9
2Product Specifications ..................................................................................................11
2.1 Package Description.........................................................................................11
2.1.1 Intel®(G)MCH Package Dimensions..................................................11
2.2 Heatsink and Clip Mechanical Reference Design..............................................11
2.2.1 Mechanical Keep-Outs.......................................................................11
2.2.2 Heatsink Assembly ............................................................................12
2.3 Thermal and Mechanical Reliability ..................................................................13
2.4 Thermal Specifications.....................................................................................14
2.4.1 External Ambient Conditions..............................................................14
2.4.2 Maximum Case Temperature.............................................................15
2.5 Temperature Measurement Metrology ..............................................................15
2.5.1 Case Temperature Measurements.....................................................15
2.5.2 90 Degree Angle Attach Methodology................................................15
2.5.3 0 Degree Angle Attach Methodology..................................................16
2.6 Power Dissipation Software ..............................................................................17
2.7 Intel®(G)MCH Thermal Design Power..............................................................18
3Generic Thermal Solution .............................................................................................19
3.1 Generic Thermal Solution Performance............................................................19
3.2 Generic Thermal Solution TIM Description........................................................19
3.2.1 The Effect of Pressure on TIM Performance......................................19
3.3 Generic Thermal Solution Thermal Operating Point..........................................20
3.4 Generic Thermal Solution Simulation................................................................20
3.4.1 Flotherm Model Implementation in a System Level Analysis..............21
3.4.2 System Model Grid............................................................................21
3.4.3 Thermal Model Power Dissipation......................................................21
4Generic Thermal Attach / Mechanical Solution..............................................................23
4.1 Heatsink Retention............................................................................................23
4.2 Thermal Bond Line ...........................................................................................24
4.3 Solder Joint Protection......................................................................................24
4.4 Intel®(G)MCH Heatsink Drawings.....................................................................25
5Vendors ........................................................................................................................27
5.1 Heatsink Suppliers............................................................................................27
Appendix A: Package Dimensions.......................................................................................................29

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4 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
Figures
Figure 1. Heatsink Assembly: Heatsink, Clip Frame, Clip Lever....................................12
Figure 2. Heatsink Assembly Placement and Actuation.................................................12
Figure 3. DIMM Airflow Measurement Location.............................................................14
Figure 4. 90 Degree Angle Attach Methodology (not to scale) .......................................16
Figure 5. 0 Degree Angle Attach Heatsink Modifications (not to scale)..........................17
Figure 6. 0 Degree Angle Attach Methodology (not to scale).........................................17
Figure 7. 0 Degree Thermal Solution Decision Flowchart for 0 °C.................................18
Figure 8. Intel®(G)MCH Components Modeled.............................................................20
Figure 9. Intel®(G)MCH Clip Assembly.........................................................................23
Figure 10. Intel®(G)MCH Clip Lateral Retention Tab Feature.......................................24
Figure 11. Intel®(G)MCH Clip Frame and Lever ...........................................................25
Figure 12. Intel®(G)MCH FC-BGA Package Dimensions (Top and Side View)..............29
Figure 13. Intel®(G)MCH FC-BGA Package Dimensions (Bottom View).......................30
Figure 14. Intel®82845GE GMCH / 82845PE MCH Keep-Out Restriction.....................31
Tables
Table 1. Specification Summary .....................................................................................8
Table 2. Reliability Validation........................................................................................13
Table 3. Maximum (G)MCH Local Ambient (TA) Recommendations..............................14
Table 4. Intel®(G)MCH Maximum Case Temperature...................................................15
Table 5. Intel®82845PE MCH Thermal Design Power ..................................................18
Table 6. Intel®82845GE GMCH Thermal Design Power...............................................18
Table 7. Chomerics T710 TIM Performance (at 50 °C as a Function of Attach Pressure)19
Table 8. TDP Dissipation for Various Airflow Speeds ....................................................20

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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 5
Revision History
Revision
Number Description Date
-002 •Corrected part number for heatsink September 2006
-001 •Initial Release. October 2002

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6 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
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Introduction
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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 7
1 Introduction
As the complexity of computer systems increases, so do power dissipation requirements. Care
must be taken to ensure that the additional power is properly dissipated. Heat can be dissipated
using improved system cooling, selective use of ducting, and/or passive heatsinks.
The objective of thermal management is to ensure that the temperature of all components in a
system is maintained within functional limits. The functional temperature limit is the range
within which the electrical circuits can be expected to meet specified performance requirements.
Operation outside the functional limit can degrade system performance, cause logic errors, or
cause component and/or system damage. Temperatures exceeding the maximum operating limits
may result in irreversible changes in the operating characteristics of the component.
The simplest and most cost-effective method is to improve the inherent system cooling
characteristics of the 82845GE GMCH /82845PE MCH is through careful design and placement
of fans, vents, and ducts. When additional cooling is required, component thermal solutions may
be implemented in conjunction with system thermal solutions. The size of the fan or heatsink can
be varied to balance size and space constraints with acoustic noise.
This document is for the 845GE and 845PE chipsets. The thermal and mechanical design
guidelines are described for both the 82845GE GMCH and 82845PE MCH. For the ICH4, refer
to the Intel®82801DB I/O Controller Hub 4 (ICH4) Thermal Design Guidelines (document
number 298651).
The thermal design guides in this document provide an understanding of the operating limits of
the 82845GE GMCH / 82845PE MCH components and discusses a generic thermal solution.
This document presents the conditions and requirements to properly design a cooling solution for
systems that use the 82845GE GMCH / 82845PE MCH. Properly designed solutions provide
adequate cooling to maintain the (G)MCH case temperature at or below thermal specification.
This is accomplished by providing a low local-ambient temperature, ensuring adequate local
airflow, and minimizing the case to local-ambient thermal resistance. By maintaining the
(G)MCH case temperature at or below those recommended in this document, a system designer
can ensure the proper functionality, performance, and reliability of the component. Table 1
summarizes the specifications discussed in this design guide.
Note: Unless otherwise specified, the information in this document applies to both the 82845GE
GMCH and 82845PE MCH. The term (G)MCH refers to both the 82845GE GMCH and
82845PE MCH.

Introduction
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8 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
Table 1. Specification Summary
Package Dimensions
(G)MCH 37.5 mm x 37.5 mm x 2.54 mm
Handling Keep out on Substrate
(G)MCH 2 mm from edge of die
Max Allowable Die Pressure
(G)MCH 400 kPa (this corresponds to 50 lbf load on die)
Heatsink Volume Keep outs
(G)MCH Heatsink X:37.5 mm, Y:37.5 mm, Z:40 mm
Operating Environment
Maximum (G)MCH Local Ambient Temperature (TA)
Assumption [For use with Intel®Pentium®4
Processors at or below the flexible motherboard 1
(FMB1) target.]
53 °C
Maximum (G)MCH Local Ambient Temperature
Assumption [For use with Intel® Pentium® 4
Processors at or below the flexible motherboard 2
(FMB2) target.]
50 °C
Minimum Airflow 50 lfm
Thermal Design Power (TDP)
82845PE MCH 5.6 W (333 MHz DDR, 533 MHz FSB, Discrete
Graphics)
82845GE GMCH 6.3 W (333 MHz DDR, 533 MHz FSB, w/ Integrated
Graphics)
(G)MCH Maximum Case Temperature
(G)MCH 92 °C

Introduction
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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 9
1.1 Definition of Terms
Term Definition
BGA Ball Grid Array. A package type defined by a resin-fiber substrate where a die is mounted,
bonded and encapsulated in molding compound. The primary electrical interface is an array of
solder balls attached to the substrate opposite the die and molding compound.
CFD Computational Fluid Dynamics.
FC-BGA Flip Chip Ball Grid Array. A package type defined by a plastic substrate where a die is mounted
using an underfill C4 (Controlled Collapse Chip Connection) attach style. The primary electrical
interface is an array of solder balls attached to the substrate opposite the die. Note that the
device arrives at the customer with solder balls attached (see Figure 8)
ICH4 I/O Controller Hub. The chipset component that contains the primary PCI interface, LPC
interface, USB, ATA-33, and other legacy functions.
EBGA Mini Ball Grid Array. A smaller version of the BGA with a ball pitch of 1.00 mm.
GMCH Graphic Memory Controller Hub. The chipset component that contains the processor and
memory interface and an integrated graphics device.
MCH Memory Controller Hub. The chipset component that contains the processor and memory
interface.
OLGA Organic Land Grid Array.
TAThe measured ambient temperature locally to the component of interest. The ambient
temperature should be measured just upstream of airflow for a passive heatsink or at the fan
inlet for an active heatsink.
TC The measured case temperature of a component. For processors, it is measured at the
geometric center of the integrated heat spreader (IHS). For other component types, it is
generally measured at the geometric center of the die or case.
TC-MAX The maximum case/die temperature with an attached heatsink. This temperature is measured at
the geometric center of the top of the package case/die.
TDP Thermal Design Power. Thermal solutions should be designed to dissipate this target power
level. Thermal Design Power (typical) is specified as the highest sustainable power level of most
or all of the real applications expected to be run on the given product, based on extrapolations in
both hardware and software technology over the life of the component. Thermal solutions should
be designed to dissipate this target power level.
TIM Thermal Interface Material. This material is designed to fill surface voids between the die and
heatsink surfaces in order to facilitate heat transfer.
lfm Linear Feet per Minute. Units of mass flow for fluids
TRHS Thermal Resistance of Heatsink.
TOP Thermal Operating Point. The TOP is defined as the thermal resistance of the thermal interface
material loaded at the design force of the clip and retention mechanism plus the thermal
resistance of the heatsink at the specified airflow speed.

Introduction
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Product Specifications
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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 11
2 Product Specifications
2.1 Package Description
2.1.1 Intel®(G)MCH Package Dimensions
The 82845GE GMCH and 82845PE MCH are in a 37.5 mm x 37.5 mm, 760 FC-BGA package
(see Appendix A).
2.2 Heatsink and Clip Mechanical Reference Design
The reference heatsink solution is a passive extruded aluminum heatsink with thermal and
mechanical interfaces. It is attached using a clip frame and mechanical advantage lever. The clip
frame is secured to the system board via four solder down anchors in four locations around the
(G)MCH.
The heatsink clip for the (G)MCH is designed to be used in conjunction with the mechanical
attach solution for the Intel®Pentium®4 processor. The clip provides a mechanical preload
applied to the heatsink and package via a mechanical advantage lever. This preload assures
minimal bond line thickness and adds rigidity to the heatsink and package assembly. The clip is
designed to prevent component damage and potential failures under environmental system
loading.
2.2.1 Mechanical Keep-Outs
The mechanical keep-out restrictions are included in Appendix A (Figure 14). The component
height restrictions are illustrated by a legend in the drawing. It is important to note that the keep-
out and height restrictions differ slightly from the Intel®82845 chipset keep-outs.

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12 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
2.2.2 Heatsink Assembly
The heatsink assembly includes the heatsink (with TIM and mechanical interface gasket), the
clip, and clip lever as shown in Figure 1. This clip attaches to solder down anchors located on
the system board.
Figure 1. Heatsink Assembly: Heatsink, Clip Frame, Clip Lever
Figure 2. Heatsink Assembly Placement and Actuation

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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 13
2.3 Thermal and Mechanical Reliability
Recommendations for thermal mechanical reliability testing are shown in Table 2. These should
be considered as general guidelines. The user, based on anticipated use conditions, should define
validation testing requirements.
Table 2. Reliability Validation
Test1Requirement Pass/Fail Criteria2
Mechanical
Shock •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,
170 inches/sec minimum velocity change.
•Setup: Mount sample board on test fixture.
Visual\Electrical
Check
Random
Vibration •Duration: 10 min/axis, 3 axes
•Frequency Range: 5 Hz to 500 Hz
•Power Spectral Density(PSD) Profile: 3.13 g RMS
Visual/Electrical
Check
Thermal
Cycling •-5 °C to +70 °C, 500 cycles Visual Check
Unbiased
Humidity •85 % relative humidity / 55 °C, 1000 hours Visual Check
Power Cycling •7,500 on/off cycles with each cycle specified as 3 minutes on,
2 minutes off 70 °C Visual Check
NOTES:
1. The above tests should be performed on a sample size of at least 12 assemblies from 3 different lots of
material.
2. Additional Pass/Fail Criteria may be added at the discretion of the user.

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14 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
2.4 Thermal Specifications
2.4.1 External Ambient Conditions
To ensure proper operation and reliability of the (G)MCH, a minimum airflow speed of 50 lfm
(linear feet per minute) must be present as measured 1 inch in front of the air inlet side of the
845GE/845PE chipset generic thermal solution. The thermal designer must carefully select the
location to measure airflow to get a representative sampling. (Note, These environmental
specifications are based on a 35 °C system external temperature measured at 5000′). The
maximum recommended local ambient air temperature (TA) for the (G)MCH is influenced by
chassis and system design. The assumptions for local ambient temperature are shown in Table 3
below and are based on an 8° temperature rise from the processor local ambient temperature.
Table 3. Maximum (G)MCH Local Ambient (TA) Recommendations
Pentium®4 Processor Flexible
Mother Board (FMB) Targets Pentium®4 Processor Local Ambient (TA) Assumptions (G)MCH Local Ambient (TA) Assumptions
FMB1 45 °C 53 °C
FMB2 42 °C 50 °C
NOTE: The values for processor local ambient temperature are provided for reference only; In case of
discrepancies, the values in the respective processor datasheet supersede the values listed above.
The amount of airflow also directly impacts the BIOS settings required for the memory thermal
management, which is controlled by the chipset. Memory thermal management needs to be set in
the BIOS for systems with under 100-lfm airflow to the (G)MCH and under 100-lfm airflow to
the memory. To determine the memory airflow, Figure 3 shows the correct location for air speed
probes in relation to the DIMM. The location of the probes (U1 and U2) should be elevated to the
center of the DIMM, and 0.25” from the edges as shown. The average should be taken from the
measurements at locations u1 and u2 shown below for determining the airspeed setting.
Figure 3. DIMM Airflow Measurement Location
0.25 in
0.25 in
U 2
U1

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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 15
2.4.2 Maximum Case Temperature
To ensure proper operation and reliability of the (G)MCH components, the temperature must be
at or below the values specified in Table 4. If the temperature of the component exceeds the
maximum temperatures listed, system or component level thermal enhancements are required to
dissipate the heat generated. Section 2.5 provides the temperature measurement metrology for
case temperature measurements.
Table 4. Intel®(G)MCH Maximum Case Temperature
Parameter Maximum (G)MCH Case
Temperature
TC-MAX 92 °C
2.5 Temperature Measurement Metrology
To accurately assess junction temperature for an application or to determine if you are not
exceeding a TC-MAX of 92 °C, it is necessary to have a good thermocouple attach. Intel has
established guidelines for the proper techniques to be used when measuring the (G)MCH case
temperature. Section 2.6 contains information on running an application program that emulates
anticipated maximum TDP. The flowchart in Figure 7 offers useful guidelines for thermal
performance and evaluation.
2.5.1 Case Temperature Measurements
To ensure functionality and reliability, the 82845GE GMCH / 82845PE MCH is specified for
proper operation when Tcase is maintained at or below its respective temperatures at 50 lfm for
the (G)MCH (see Table 4). The surface temperature at the geometric center of the die
corresponds to the maximum Tcase or TC-MAX.
2.5.2 90 Degree Angle Attach Methodology
1. Use 36 gauge or smaller K-type thermocouples.
2. Ensure that the thermocouples have been properly calibrated.
3. Attach the thermocouple bead or junction to the top surface of the die in the center using
high thermal conductivity cement. It is critical that the thermocouple bead makes contact
with the die.
4. The thermocouple should be attached at a 90-degree angle if there is no interference with the
thermocouple attach location or leads (see Figure 4). This is the preferred method and is
recommended or use with both bare packages as well as packages employing a thermal
solution.
5. The hole size through the heatsink base to route the thermocouple wires out should be
smaller than 3.3 mm (0.13 inches) in diameter.
6. Make sure there is no contact between the thermocouple cement and the heatsink base. This
contact will affect the thermocouple reading.

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16 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
Figure 4. 90 Degree Angle Attach Methodology (not to scale)
90° Angle Attach
3.3 mm (0.13 in.)
Diameter Hole
Thermocouple Bead
Die
Substrate
Heatsink
Thermocouple Wire
2.5.3 0 Degree Angle Attach Methodology
1. Mill a 3.3 mm (0.13 inches) diameter hole centered on bottom of the heatsink base
(see Figure 5). The milled hole should be approximately 1.5 mm (0.06 inches) deep.
2. Mill a 1.3 mm (0.05 inches) wide slot, 0.5 mm (0.02 inches) deep, from the centered hole to
one edge of the heatsink. The slot should be in the direction parallel to the heatsink fins (see
Figure 5 and Figure 6.
3. Attach thermal interface material (TIM) to the bottom of the heatsink base.
4. Cut out portions of the TIM to make room for the thermocouple wire and bead. The cutouts
should match the slot and hole milled into the heatsink base.
5. Attach a 36 gauge or smaller calibrated K-type thermocouple bead or junction to the center
of the top surface of the die using a high thermal conductivity cement. During this step,
make sure there is no contact between the thermocouple cement and the heatsink base
because any contact will affect the thermocouple reading. It is critical that the
thermocouple bead makes contact with the die (see Figure 5).
6. Attach heatsink assembly to the (G)MCH and route the thermocouple wires out through the
milled slot.

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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 17
Figure 5. 0 Degree Angle Attach Heatsink Modifications (not to scale)
Angle_Attach_Heatsink_Mod
1.3 mm (0.05 in.)
(0.5 mm (0.02 in.) Depth)
3.3 mm (0.13 in.) Diameter
(1.5 mm (0.06 in.) Depth)
Figure 6. 0 Degree Angle Attach Methodology (not to scale)
angle_attach_1
Thermocouple Wire
Die
Cement +
Thermocouple Bead
Substrate
2.6 Power Dissipation Software
The power simulation software is a utility designed to dissipate the Thermal Design Power
(TDP) on the (G)MCH when used in conjunction with an Intel®Pentium 4 processor. The
combination of the Intel®Pentium 4 processor and the bandwidth capability of the (G)MCH
enable new levels of system performance. To assess the thermal performance of the
845GE/845PE chipset generic thermal solution during “worst-case realistic application”
conditions, Intel has developed a software utility that operates the chipset at near worst-case
power dissipation.
The utility has been developed solelyfor testing customer thermal solutions at or near the
thermal design power. Figure 7 shows a decision flowchart for determining thermal solution
needs. Real future applications may exceed the thermal design power limit for transient time
periods. For power supply current requirements under these transient conditions, refer to each

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18 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
component’s datasheet for the ICC (Max Power Supply Current) specification. Contact your Intel
Field Sales representative to obtain a copy of this software.
Figure 7. 0 Degree Thermal Solution Decision Flowchart for 0 °C
flowchart
Attach thermocouples using
recommended metrology.
Setup the system in the
desired configuration.
No
Yes
Heatsink
required
Select
Heatsink
End
Start
Run the Power
program and
monitor the device
die temperature.
Attach device to
board using normal
reflow process.
Tdie >
Specification?
2.7 Intel®(G)MCH Thermal Design Power
The 845GE/845PE chipset power utility is designed to dissipate the TDP power value through
the (G)MCH when a system is populated with the memory listed in Table 5. These values have
been validated for the configurations below running the Processor System Bus frequency at 400
MHz.
Table 5. Intel®82845PE MCH Thermal Design Power
TDP (Watts) System Configuration
5.6 W 333 MHz DDR, 533 MHz FSB, Discrete Graphics
Table 6. Intel®82845GE GMCH Thermal Design Power
TDP (Watts) System Configuration
6.3 W 333 MHz DDR, 533 MHz FSB, w/ 266 MHz Integrated Graphics

Generic Thermal Solution
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Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide 19
3 Generic Thermal Solution
3.1 Generic Thermal Solution Performance
If the thermal designer is able to provide greater than 50 lfm at the air inlet side (upstream) of
the heatsink, the case temperature of the (G)MCH will decrease. Since the thermal resistance of
the package and thermal interface material (TIM) remain constant for all upstream airflow
speeds, the case temperature behavior is due to the decreased thermal resistance (°C/W) of the
82845GE GMCH / 82845PE MCH generic thermal solution’s heatsink. Hence, if a thermal
designer can provide greater than 50 lfm upstream of the heatsink, the junction temperature will
be reduced. This reduction in junction temperature leads to greater component reliability.
3.2 Generic Thermal Solution TIM Description
A thermal interface material is used to provide improved conductivity between the die and
heatsink. The reference thermal solution uses Chomerics* T-710, 0.127 mm (0.005 inches)
thick, 12.7 mm x 12.7 mm (0.5 inches x 0.5 inches).
3.2.1 The Effect of Pressure on TIM Performance
As mechanical pressure increases on the TIM, the thermal resistance of the TIM decreases. This
phenomenon is due to the decrease of the Bond Line Thickness (BLT). The effect of pressure on
the thermal resistance of the Chomerics T710 TIM is shown in Table 7. The heatsink clip (see
Figure 1) provides enough pressure for the TIM to achieve a thermal conductivity of 0.9 W/m⋅K.
Table 7. Chomerics T710 TIM Performance (at 50 °C as a Function of Attach Pressure)
Pressure (psi) Thermal Resistance
(°C*In2)/W
5 0.37
10 0.3
20 0.21
50 0.17

Generic Thermal Solution
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20 Intel®845GE / 845PE Chipset (G)MCH Thermal Design Guide
3.3 Generic Thermal Solution Thermal Operating Point
The Thermal Operating Point (TOP) is defined as the thermal resistance of the TIM at the
design force of the clip and retention mechanism plus the thermal resistance of the heatsink at
the specified airflow speed. The thermal resistance of the heatsink (TRHS) is given by the
following equation:
TRHS = (Tcase – Tlocal_ambient) / (% TDP dissipated via heatsink)
Thermal simulation results show that as airflow increases upstream of the 845GE/845PE chipset
generic thermal solution, the percentage of TDP that leaves via the top of the package increases
(see Table 8).
Table 8. TDP Dissipation for Various Airflow Speeds
Upstream Airflow Speed
(lfm) % of TDP Dissipated via
Intel Thermal Solution % of TDP Dissipated via the 4-Layer JEDEC Board
50 70% 30%
100 75% 25%
150 77% 23%
3.4 Generic Thermal Solution Simulation
A Computational Fluid Dynamics (CFD) model of the (G)MCH has been developed for use with
the commercially available thermal analysis tool “Flotherm” (version 2.1 or later). This model
can be used to evaluate package thermal limits and cooling methods. Modeled (G)MCH
components are shown in Figure 8.
Figure 8. Intel®(G)MCH Components Modeled
package_overview
Die
C4 Bumps
Substrate
Underfill
Contact your Intel Field Sales representative to order the thermal models and user’s guides.