Guidelines

Thermal Mechanical Design
24 Dual-Core Intel
®
Xeon
®
Processor 7000 Sequence Thermal /Mechanical Guidelines
The case-to-local ambient thermal characterization parameter of the processor,
CA
, is comprised of
CS
, the TIM thermal characterization parameter, and of
SA
, the sink-to-local ambient thermal characterization parameter:
Equation 2-4.
CA
=
CS
+
SA
Where:
CS
= Thermal characterization parameter of the TIM (°C/W).
SA
= Thermal characterization parameter from heatsink-to-local ambient (°C/W).
CS
is strongly dependent on the thermal conductivity and thickness of the TIM between the
heatsink and IHS.
SA
is a measure of the thermal characterization parameter from the bottom of the heatsink to the
local ambient air.
SA
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.
Figure 2-9 illustrates the combination of the different thermal characterization parameters.
2.3.2.1 Example
The cooling performance,
CA,
is then defined using the principle of thermal characterization
parameter described above:
• Define a target case temperature T
CASE-MAX
and corresponding TDP at a target frequency, F,
given in the processor Datasheet.
• Define a target local ambient temperature at the processor, T
LA
.
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.
Figure 2-9. Processor Thermal Characterization Parameter Relationships