Is there any benefit to putting a 92mm or 120mm fan over an 80mm hole if there's room to mount the larger fan, or should I just stick with an 80mm?


Thanks guys!

I haven't tried it, so I don't know for sure, but a larger fan might be able to push a little more air through the vent hole. I suspect there would be some feedback and additional turbulence though, since the outer area of the blades will be pushing air flat against a wall. If you use an adapter duct, that might solve the problem and give you full air flow.

This place has a good selection of ducts: http://jab-tech.com/Fan-adpters-and-ducts-c-171.html. They use the same stock photo for most of them.

make it a 92mm hole...

+1

Hi, the swept area of the blades of an 92mm fan (84mm blades, 25mm hub) is about 5050mm2. That's equivalent to a hole 80mm across, the hole in your case will be smaller than 80mm, eg a 74mm hole gives 85% of the swept area of fan.
I think a 92mm fan on a 92-80mm adaptor on an open hole will have better air-flow/noise ratio than original 80mm fan. If have any sort of fan grill/cover over the hole it will need to go!
I made adaptor to put 2x92mm fans in place of 2x80mm on back of my case and it definitely helped. The case originally had 1x 80mm fan so it's now "a bit hacked"
Regards, Seb

Remember that adage about square peg in a round hole? Reverse it and you see the issue with most fan mounts: you're putting a round shape on a square one, resulting in dead or wasted space.

Most custom/scratch case work will include round fan holes. Why? Because a square fan hole will not be fully covered by a fan the same size, as SebRad illustrates nicely. A 120mm fan attached to a 120mm square hole will leave dead space in the corners. A 140mm fan will cover a square 120mm hole nicely, but then leave wasted potential as the fan blades sweep over not-hole areas. Makes you wonder why case makers make square fan holes at all...