Thermally Advantaged Tested Chassis Guide

Section 2
E34579 / TAC 2.0 Design Guide 9
2.3 System Fans
Rear Chassis System Exhaust Fan:
The chassis mounted system fan remains a critical part of the overall system solution.
The rear exhausting system fan contributes to the intended low internal pressure that
forces cooler external air to flow into the system vent(s). A 92mm rear fan is
recommended however there are many options that will perform adequately. It is
critical to design the vent opening for the rear chassis fan to minimize back pressure
so that it does not overly restrict the exhaust air flow. The chassis designer is
responsible for selecting the appropriate rear exhaust fan and corresponding vent
design for a given application.
Power Supply Fan:
The power supply fans seen in the market today in general have shown to be
adequate to support the overall system air flow design intent defined in this
document. The power supply fan must exhaust the internal chassis air outside of the
system to assist with internal cooling. A power supply fan that pressurizes the chassis
could render the TAC 2.0 vent configuration ineffective. No changes or special
considerations beyond air flow direction are intended for power supplies in this design
guide.
Note: Some enclosure designs may utilize system pressurizing via intake fans for
thermal management. This is a design choice that is not intended or recommended in
the scope of the TAC 2.0 Design Guide.
Processor Active Fan Heat Sink:
Much the same as the rear system and power supply exhaust fans, the processor
cooling fan remains a critical piece of the overall system cooling solution. An active
CPU fan heatsink with airflow directed towards the main board is assumed in the TAC
2.0 Design Guide and is needed to properly cool the processor and surrounding
components.
Optimized chassis airflow will directly minimize the performance requirements (and
cost) of internal heat dissipation devices such as processor fan heatsinks.