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6700PXH 64-bit PCI Hub Thermal/Mechanical Design Guidelines 17
6 Reference Thermal Solution
Intel has developed one reference thermal solution to meet the cooling needs of the PXH component
under operating environments and specifications defined in this document. This chapter describes
the overall requirements for the reference thermal solution including critical-to-function dimensions,
operating environment, and validation criteria. Other chipset components may or may not need
attached thermal solutions, depending on your specific system local-ambient operating conditions.
6.1 Operating Environment
The PXH reference thermal solution was designed assuming a maximum local-ambient temperature
of 55°C. The minimum recommended airflow velocity through the cross section of the heatsink fins
is 200 linear feet per minute (lfm). The approaching airflow temperature is assumed to be equal to
the local-ambient temperature. The thermal designer must carefully select the location to measure
airflow to obtain an accurate estimate. These local-ambient conditions are based on a 35°C external-
ambient temperature at sea level. (External-ambient refers to the environment external to the
system.)
6.2 Heatsink Performance
Figure 6-1Figure 6-1Figure 6-1 depicts the measured thermal performance of the reference thermal
solution versus approach air velocity. Since this data was measured at sea level, a correction factor
would be required to estimate thermal performance at other altitudes.
Figure 6-1. Reference Heatsink Measured Thermal Performance Versus Approach Velocity
3.5
4.0
4.5
5.0
5.5
6.0
50 100 150 200 250 300
Flow Rate (LFM)
ca (°C/W)