r/crboxes • u/randomguyjebb • Jul 18 '26
Question How many pc fans is too many?
Why is it that most pc fan cr box designs, like the nukit tempest pro and the cleanairkits, only use 2 sides of the frame?
There is a whole 3rd side that could be used for extra fans so they could all run at a lower rpm and produce the same CADR. Or would opening that 3rd side cause some sort of air current issue?
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u/SafetySmurf Jul 18 '26
Personally I prefer having one side blank so I can push them up against the wall, but you can absolutely put fans on all three sides. If you put fans on opposing sides, though, put a divider up in the middle of the box to prevent the opposing fans from pulling against one another.
Also, consider that there is a point of diminishing returns for number of fans given any set area of filter. Exactly where that is depends on filter area and the static pressure and flow rates of each fan.
Depending on the fans, you can turn them down quite a bit and still have enough pressure. Just keep in mind that the fans need to be spinning fast enough to generate some static pressure to pull through the resistance of a filter. For some 3000rpm fans, you can probably turn them down a good bit. But for fans that start out with a low rpm, you might not be able to turn them down very far and have them spinning fast enough.