I have changed out quite a few fans over the years, you know the ones that I’m talking about, they make your PC sound like it’s a jet engine on takeoff. A few times I blew the dust out of the fan, pried the fan blade off and dropped a few drops of oil into the fan shaft. This seemed to always fix the problem but in my case it always turned out to be a temporary fix since the squeal usually came back after a few weeks of operation and when I opened it there was a bunch of black gunk in the shaft. I think I see what my problem was after reading this PC Fan Repair post from hacklordsniper. I should have used bearing grease and perhaps cleaned the fan assembly better. Seems that he is quite a bit more invasive than I have ever been since he utilizes the bath tub to clean fans and other electronic parts.
Via: EEVblog Forum
“You will need it later. Remove the rubber seal, then use tweezers to remove white lock and a small rubber seal again. At this moment the fan will fall apart and you will see why it does not work. Clean all parts, apply ball bearing grease (not regular one, but the one designed for small bearings) to axle and top and bottom of fan. Reassemble and test”
