[razan fadel]

I've realized that I need to add a fan at the back of my case since my new power supply doesn't draw the air out.

There's a pre-made hole in the case, and I've measured from the top of one screw hole to the bottom of the other - exactly 90mm. However, when I go to look at fans there are listings for 90mm & 92mm. One site claims that these are actually the same size - just listed differently. Is this true? If not, do I need the 92mm since the fan's overall dimensions extend a bit further than the holes?

[Carbon]

90mm is already pretty weird. Usually it's 80mm and 120mm. It's likely to be the same size.

[4D(Fordy(Ford) Ollie]

Those measurements are -or should be- for the screw holes.

Often the fan diameter and the screwhole gap is the same, to avoid confusion, but in this sort of scenario you're best off going by screwholes.

So best bet would be a 90mm one, which are more commonplace than 92mm (although still very rare! )

I think I read somewhere that the 92 had come about as a fan specifically for something or another, but was then used in 90mm gaps, which did work, just not quite a clean fit.