Intel
®
945G Express Chipset GMCH Thermal Design Guide
Reference Thermal Solution
4
Reference Thermal Solution
The reference component thermal solution for the Intel
®
945G Express Chipset GMCH for 1U
and larger server platforms utilizes a wire clip and motherboard anchors. This chapter provides
detailed information on operating environment assumptions, heat sink manufacturing, and
mechanical reliability requirements for the GMCH. For information on the Intel
®
ATX and BTX
reference design for the GMCH heat sink refer to the
Intel
®
945G/945P Express Chipset Family
Thermal and Mechanical Design Guidelines
.
4.1
Operating Environment
The operating environment of the GMCH will differ depending on system configuration and
motherboard layout. This section will define operating environment boundary conditions that are
typical for 1U server form factor. The system designer should perform analysis on platform
operating environment to assess impact to thermal solution selection.
4.1.1
1U Form Factor Operating Environment
The reference thermal solution compatible with the 1U form factor was designed assuming a
maximum local ambient air temperature, T
LA
, of 55° C with a minimum airflow velocity of 200
lfm (1.02 m/s) present 25 mm (1 in.) directly in front of the heat sink air inlet side. The system
integrator should note that board layout may be such that there will not be 25mm (1 in.) between
the processor heat sink and the GMCH. The potential for increased airflow speeds may be realized
by ensuring that airflow from the processor thermal solution exhausts in the direction of the
GMCH heat sink. In addition, GMCH board placement should ensure that the GMCH heat sink is
within the air exhaust area of the processor heat sink. An example of typical 1U server layout is
shown in Figure 6. This layout is based on the Thin Electronics Bay specification located at
http://www.ssiforum.org
.
Assuming these boundary conditions are met, the reference thermal solutions will meet the
thermal specifications for the 945G GMCH. Table 4 shows the required thermal performance for
the GMCH. The thermal designer must carefully select the location to measure airflow to get a
representative sampling. These environmental assumptions are based on a system at sea level.
Table 4 GMCH Thermal Requirements
TDP (W)
Required
Ψ
CA
at T
LA
= 55° C
22.2 1.98°
C/W
NOTE:
T
LA
is defined as the local (internal) ambient temperature measured directly upstream from the heat
sink airflow inlet.
The thermal performance of the reference thermal solution for the Intel
®
945G Express Chipset
GMCH for the 1U server form factor is show in Figure 5. This figure shows the performance of
the reference thermal solution at sea level based on lab test data. This testing does not imply any
statistical significance and was performed to verify that the thermal solution is performing within
expectations. It is the responsibility of the system integrator to perform validation on the entire
thermal solution including heat sink, thermal interface material, and attach mechanism.
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