Atx Form Factor Operating Environment; Table 3. (G)Mch Heatsink Boundary Condition Summary In Atx Platforms - Intel 4 Series Thermal/Mechanical Design Manuallines

Reference Thermal Solution
4.1.1

ATX Form Factor Operating Environment

The (G)MCH reference design thermal solution has been optimized to meet all three
boundary conditions for 65W/95W/130W processor TDPs. The highest processor TDP
provide a boundary condition for the (G)MCH heatsink with higher air inlet speed and
temperature (T
temperature. The (G)MCH heatsink design is required to meet all of these boundary
conditions as specified in Table 3.

Table 3. (G)MCH Heatsink Boundary Condition Summary in ATX Platforms

Processor TDP
In ATX platforms using the 130 W TDP processor, an airflow speed of 1.73 m/s
[341 lfm] is assumed to be approaching the heatsink at a 30° angle from the
processor thermal solution, see Figure 8 and Figure 9 for more details. The local
ambient air temperature, T
be 51.6 °C for the (G)MCH. The airflow assumed above can be achieved by using a
processor heatsink providing omni directional airflow, such as a radial fin or "X"
pattern heatsink. Such a heatsink can deliver airflow to both the (G)MCH and other
areas like the voltage regulator, as shown in Figure 10. In addition, (G)MCH board
placement should ensure that the (G)MCH heatsink is within the air exhaust area of
the processor heatsink.
Note that heatsink orientation alone does not guarantee that airflow speed
will be achieved. The system integrator should use analytical or experimental means
to determine whether a system design provides adequate airflow speed for a
particular (G)MCH heatsink.
The thermal designer must carefully select the location to measure airflow to get a
representative sampling. ATX platforms need to be designed for the worst-case
thermal environment, typically assumed to be 35 °C ambient temperature external to
the system measured at sea level.
23
) while the lowest processor TDP provides lower air inlet speed and
A
(TDP)
65 W
95 W
130 W
, at the (G)MCH heatsink in an ATX platform is assumed to
A
Airflow Speed
(LFM)
245
292
341
Thermal and Mechanical Design Guidelines
Air Inlet Temperature
(T )
A,
°C
47.2
°C
50.0
°C
51.6