Needing a secondary case fan for my current PC build, I picked up an Antec Tri-Cool Double Ball Bearing fan, the 92 mm size. Even on its highest speed, I found it to be quieter than the fans in the PCs on my desk at work. On its lowest setting, you pretty much can’t hear it at all. At its full retail price of $25, I wouldn’t bother with it, but when it’s on sale for less than $10, that’s not bad.
When buying a fan, you always want the biggest fan that will fit your case, as a larger fan can get away with spinning more slowly while still moving an acceptable amount of air. The slower the fan spins, the quieter it will be.
My biggest complaint with the fan is its switch. It comes on a flat cable that, presumably, you’re supposed to just run through the top of the case before putting the cover on. There’s no way to mount it, that I can see. I would have preferred they put some threaded holes in the sides of the switch, so I could cut an opening in the case and bolt it into place, or put it on some kind of a bracket. Not all cases have openings in the back where you could mount the bracket, which is probably why they designed it the way they did, but having some way to securely mount it to the back of the case would have been nice, even if that meant modifying the case.
If I had it to do over again, I probably would have paid the extra $5 or so for an Antec Smartcool with a thermal sensor on it, so that it automatically would change speeds as system temperature changes. Then there’s no need for the switch, and no reliance on a human to remember to flip the switch when starting something that will make the system work hard.
I don’t insist on my PCs being silent, but having spent about two years of my career sitting on a computer room floor surrounded by the servers I was administering, I don’t want my computers to be loud, either.