Originally Posted by
tielknight
A clicking-sound is generally the ball bearings going out from what i've experienced. You can try cleaning it with canned air but, honestly, once they start clicking, you better start looking for a replacement as it will seize-up sooner or later and you do not want to be stuck with a dead component and not having a replacement-part.
Heavier loads on the PSU make the fan spin faster(at least it should, common sense and all that) to keep that sucker breathing so only makes sense that when it speeds up, the faster the metal (potentially) grinds against itself and the louder it gets.
Went through something similar with a stock cooler on my GPU(barely 6-months old when the problem started) and it started out as a slow click-click that ended up making lovely grinding-sounds when I started playing heavy-load games and after about a month it just flat-out refused to spin up on start-up. I flicked the fan to get it started again but that was only a band-aid solution that gave me enough time to order a replacement-fan and that baby has been humming along nicely for damn near 5-years now.