Guide · PC case airflow
Case airflow: which way your fans should blow
Should case fans be intake or exhaust?
Front and bottom in, rear and top out, with a little more in than out so dust stays on the filters.
AIO radiator: top or front?
Top, as exhaust: the CPU's heat leaves where warm air rises anyway. In front it feeds the CPU cool air but warms everything after it.
What is a reverse-blade fan?
A fan with mirrored blades: it pulls air in through its struts, so the clean side and its lights face the glass.
Everything below is live. Click a glowing to add a fan, click it again to flip it or take it out, drag to turn the case.Air moves at a fifth of its real speed.
Which way does a fan blow?
Air leaves on the side with the struts holding the motor. The two small arrows on the frame edge say the same.
Reverse-blade fans look the same but have mirrored blades, so the air goes the other way: in through the struts, out of the blade side. They exist for glass cases. A fan on the side or the bottom has to pull air in, and a normal one would show you its struts and cable; a reverse-blade one does the same job with its clean blade side and lights facing the glass. Lian Li, Phanteks and others sell them next to their standard fans. With one of those, the struts rule flips: trust the arrows on the frame. Spinning a fan backwards doesn't reverse it; only turning it round or buying reverse blades does.
Positive or negative pressure
Positive: intake > exhaust
The surplus has to leave, so it escapes through PCIe slot covers, empty fan slots and panel seams. Nothing gets in except through the filtered intakes. The usual pick: a little more intake than exhaust, for example three front intakes against one rear exhaust.
Negative: exhaust > intake
The case sucks air in through every gap, filtered or not. Temperatures can be fine, since hot air leaves quickly, but dust builds up on the GPU and around the rear slots. Try “Mostly exhaust” above and watch the amber streaks.
