Intel QX9770 Design Guidelines - Page 25

Thermal Metrology 3.1.1 Example The cooling performance, ΨCA, is then defined using the principle of thermal characterization parameter described above: • The case temperature TC-MAX and thermal design power TDP given in the processor datasheet. • Define a target local ambient temperature at the processor, TA. Since the processor thermal profile applies to all processor frequencies, it is important to identify the worst case (lowest ΨCA) for a targeted chassis characterized by TA to establish a design strategy. 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 specific Intel processor thermal specifications, and are for illustrative purposes only. Assume the TDP, as listed in the datasheet, is 100W and the maximum case temperature from the thermal profile for 100W is 67 °C. Assume as well that the system airflow has been designed such that the local ambient temperature is 38°C. Then the following could be calculated using equation 1 from above: ΨCA = (TC,- TA) / TDP = (67 - 38) / 100 = 0.29 °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 were designed to work with a TIM material performing at ΨCS ≤ 0.10 °C/W, solving for equation 2 from above, the performance of the heatsink would be: ΨSA = ΨCA − ΨCS = 0.29 − 0.10 = 0.19 °C/W Thermal and Mechanical Design Guidelines 25