Nettop Platform for 2008 System Design White Paper

Improving System Thermal Performance
White Paper 31
5.4 Summary
The case studies summary in Table 8 shows that in order to enable an effective
passive thermal design boundary condition, the placement of power supply unit (PSU)
fan and the system fan is critical.
For PSU fan, it’s is obvious that placing it closer to processor heatsink is capable to
provide excellent airflow. Need to take note that the processor heatsink is placed
within coverage of PSU fan. On the other hand, placing a PSU fan at location (E)
faraway from motherboard is not preferred.
For system fan, the excellent position is found at (F), which is located on top of
processor heatsink. System fan (F) provides impingement airflow to cool processor
and the other components on the motherboard. System fan (B) & (C) are able to
provide good boundary conditions as well, depending on fan size & location relative to
heatsink. System fan (D) is inefficient since it is too far way from the motherboard.
The result shows that PSU fan (A) & System fan (F) are critical for passive design.
These two fan locations are capable to provide excellent boundary condition to enable
simple, low cost passive heatsink design.