Yeah, Corsair PSU's are noisy. Wait, do you have a corsair PSU or just corsair fan? Anyway, really you need a dedicated PSU fan, and the best ones are made by Sanyo Denki, i.e., the San Aces. Google it. But they're expensive. And they're not that much quieter. But they are better than what you got now.
Also working on PSU can be dangerous. It has high voltage inside. Also you really should try to fully discharge the capacitors before you open it up. If you don't you might get a hella shock, which ain't too bad, but also a burn, which is bad, or if you are dumb enough to be holding the PSU with both hands the shock will go across your chest and through your heart which may or may not be bad, depending on the amount of voltage in the charge viz. the strength of your heart.
Finally PSU fans are either soldered or they have those funky mini-three-pin molex connectors, which are not easy to source. Best advice is to get a new PSU. Preferably fanless, like this one (as long as your rig doesn't suck more than 520W at peak, which means no SLI):
http://www.amazon.com/Seasonic-SS-520FL-Fanless-Platinum-ATX12V/dp/B009VV56TO. I don't have one of those Seasonic 520Watters, but I want one for my next build. Seems like the answer to PSU noise that I've been waiting for, for 10 years now.