Airflow: Unique To Downward-Facing Blowers
Downward Blowers (Top-Down Coolers)
The boxed heat sink and fan combos you get from AMD and Intel are not particularly efficient because their airflow is not aligned with a vent in the chassis. So, they blow straight down onto the motherboard. On the upside, the motherboard's power logic gets a bit of cooling assistance. But it's up for debate whether that makes up for limited performance and more noise. We've noticed the boxed coolers from AMD are particularly guilty, barely pushing enough air to keep the 125 W processors running well, and often spinning at up to 6000 RPM, generating obnoxious levels of noise.
As with the other cooling setups, the rest of the components, the chassis, and the built-in fans play an important role when using downward-facing blowers.
The above machine receives insufficient active airflow. There’s no rear ventilation, and the graphics card blocks the effects of convection even further.
That's better! This setup allows even a retail boxed cooler to dissipate heat effectively.
Assembly Options
Optimization with Side Ventilation
The often-slandered side fan actually makes a lot of sense if you're using a downward-facing blower, since cool air coming through the vents is blown right onto the CPU cooler's intake. Remaining components also stand to benefit from these vents, so they can really be worthwhile:
You can either choose to use a case with a big, slow, and quiet fan like the LC-Power Titus...
...or you opt for a model with a couple of 12-cm fans, like on this Enermax Hoplite:
