<< I want to quiet down my pc if you can't tell from my HS post. I searched the forums for tips on fan replacement for power supplies but didn't come up with much. What kind of specs do I have to look at when looking for the right fan. I know they are generally 80mm, but what about other details? What kind of fans will keep it cool enough? What kind of fans will give me the right regulation? etc, etc, etc.... >>
What kind of powersupply do you have?? usually name brand PSUs such as Antecs have good cooling design so you dont need a high speed fan as much as generic PSUs. If I were you, I'd start by doing some ressearch and find out your current fans CFM and noise level in DBA. Generally, You want higher CFM and lower DBA so start from there.
I have an enermax whisper series PSU which was designed to be quiet. It monitors system temp and adjusts fan speed automatically.