Is a CPU fan safe to be used as a case fan?

Is it OK to use a CPU fan as a case fan, given that he wires are different colours? I obviously have to plug it into case fan pins as the CPU fan pins are already taken up…

I have an old fan off an MD CPU heatsink here, wired red, black and white. Any probs using it in a case or will it do something nasty to my mobo?

I can’t find any wiring diagrams or anything to show what’s what.

I wouldn’t bother, most factory cpu fans move little air and it wouldn’t be worth it.

The white lead is probably an RPM sensor, and can be left off. As long as the fan has adequate RPM and CFM ratings, it should be a decent case fan.

You want the new fresh air to come in from the direction you choose and blow out in a different direction. So the air flows through the case in and out.

Don’t make the fans work against each other.

Thanks, yeah I know that.

I suspected that the power wires were in the same place and the 3rd was a sensor, just wanted to check,. It’s not a replacement as a case fan; it just adds a little bit extra on a small space that’s available.

[QUOTE=groovemeister;2022740]Thanks, yeah I know that.

I suspected that the power wires were in the same place and the 3rd was a sensor, just wanted to check,. It’s not a replacement as a case fan; it just adds a little bit extra on a small space that’s available.[/QUOTE]

Be aware that case ventilation is not as straight-forward as it may appear. You need to have nearly equal CFM ratings on the fans that blow in and the fans that blow out. Too much negative pressure causes air to get sucked in through places like optical drives, and the resulting deposition of dust. Too much positive pressure causes similar issues, plus it can actually interfere with cooling of the CPU, vid card, etc. Most cases are designed to cause specific air flow currents over the board and CPU, with the PSU serving as a heat port from the CPU. Mess with that and you may actually wind up with a hotter CPU or vid card, or hotter drives.

Slight negative pressure is generally considered optimal. But not so much that the PSU is not blowing out enough heat.

Erk.

Thanks. It is only an old PC that doesn’t have much in the way of fans anyway. Hmmm…