How do I know which fan to get?

[ddeder]

I need to put an exhaust fan in the back of my computer. I see there are high, medium and low RPM exhaust fans. How do I know which speed to get? Also, is 80MM pretty standard in most cases?

I posted this in the general hardware forum as well, but nobody has an answer for me there!

Thanks.

 

[Electric Amish]

It depends on what other fans you have in your case. You want to balance the amount of intake air and exhaust air so that the delta is just above zero.

amish

 

[ddeder]

The only other fans in the case are the one in the power supply and the CPU fan. The power supply is a deer 250W which is vented out the front of the PSU (not recommended by AMD, but I didn't know that when I bought the case). AMD does not recommend a fan in the front of the case.