This shows how behind-the-times I am
I was looking at computer power supplies, and they call have the fans in the top
I was thinking this would take a special case with a hole in the top to draw in air from the outside but that's not correct is it
Will draw air from inside same as any other power supply?
Power supply at the top but with the fan at the bottom, the fan sucks air outside
So it must be the one with the fan at the top suck air rather than blow air?
There was a case I was looking at that had the power supply at the bottom. Closer look, and there is an opening with a filter there. The filter wouldn't be necessary unless it was pulling air from outside.
The normal PC case is ATX, the one you saw is mATX
Modern cases (= give or take those where middle tower = standard ATX size stopped meaning "4 optical drives") tend to have it on the bottom regardless of size, allegedly because that way it sucks in colder air which obviously improves efficiency of the PSU's heatsinks; I just think it looks ugly!
FWIW the only such modern case I have, a Cooler Master Elite 110, has it on top and allows you to install it either side up 😀
Air direction is a separate thing, when ATX was new it was intended to use the PSU fan as the only one for lower end systems so it pushed air inside, by the turn of the millennium this was abandoned and now they all suck from the inside!
Somewhere between these two events, therefore in the 2000s, it became trendy to have case fans, sometimes a ridiculous amount of them... all while common motherboards went from 3 fans (invariably labeled CPU/Chassis/Power) to two 😀