Processor Thermal Characterization Parameter Relationships - Intel X5365 - Xeon 3.0 GHz 8M L2 Cache 1333MHz FSB LGA771 Quad-Core Processor Design Manual

Figure 2-15. Processor Thermal Characterization Parameter Relationships
2.3.2.1 Example
The cooling performance, Ψ
characterization parameter described above:
• Define a target case temperature T
processor Datasheet.
• Define a target local ambient temperature at the processor, T
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.
Assume as well that the system airflow has been designed such that the local processor
ambient temperature is 45°C. Then the following could be calculated using equation
(2-3) from above:
Equation 2-5.Ψ = (T
CA
To determine the required heatsink performance, a heatsink solution provider would
need to determine Ψ
configuration. If the heatsink solution was designed to work with a TIM material
performing at Ψ
of the heatsink would be:
Equation 2-6.Ψ = Ψ
SA
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:
Equation 2-7.Ψ = (T
CA
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.
36
is then defined using the principle of thermal
CA,
– T ) / TDP = (68 – 45) / 85 = 0.27 °C/W
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performance for the selected TIM and mechanical load
CS
≤ 0.05 °C/W, solving for equation (2-4) from above, the performance
CS
= 0.27 − 0.05 = 0.22 °C/W
− Ψ
CA CS
– T ) / TDP = (68 – 40) / 85 = 0.33 °C/W
CASE LA
Quad-Core Intel® Xeon® Processor 5300 Series Thermal/Mechanical Design Guidelines (TMDG)
Thermal/Mechanical Reference Design
and corresponding TDP, given in the
CASE_MAX
.
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