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Does the fan go on the bottom or top of the power supply?

which way should the fan (top-big fan) face when installing a Power supply unit? to the top or down? Does it matter?

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marked as duplicate by Jeff Atwood Aug 19 '09 at 0:50

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

related:… – hyperslug Aug 18 '09 at 23:36

It all depends on what airflow you want and how much heat you are dealing with, I guess!

EDIT: Assuming the large fan takes air into the PSU and it vents out the back...

If it's a traditional top-mount PSU position in the case, fan facing into the PC case is the most usual mounting, but if you have a hot PC and not much other ventilation, you will be pulling hot air through your PSU (though if you have a good airflow through the case this won't be too much of a problem as it won't get hotter than the inside of a PSU).

If the case has a small gap above the PSU, or even better a vented area above the PSU, installing it facing up would mean you are drawing cooler air through it.

Most cases that mount the PSU in the bottom that I've seen have a vented area in the base of the case, so the intention is to mount fan-down. Rather like the Antec P180 my old PC lives in.

If you look at any markings on the back of the PSU, and such aesthetics bother you, mount it so they are upright when the PC is in use! ;^)

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Make sure that the fan is facing inwards (so down if the PSU is mounted at the top of the case) towards the open space of the case and away from the actual casing. The fan will suck hot air from the CPU/case and blow it out of the back of the case.

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