I have a third generation 80GB PS3 which recently has started getting a very, very noisy fan within a few minutes of turning the system on (before even playing a game sometimes), like so noisy I have to crank my AV amp up just to hear in-game audio. The noise is from the fan speed and movement of air, as opposed to some kind of obstruction on the fan or the optical drive.
I recently took the thing apart entirely (like, literally every part that wasn't soldered) and gave it a thorough clean, as well as re-apply good quality thermal paste to the CPU and GPU, however it's done nothing to reduce the noise.
High fan speeds suggest overheating, however the console doesn't feel in the least bit hot, and the exhausted air isn't particularly warm either. Orientation of the PS3 doesn't seem to affect it, it has more than the recommended clearance around it
Any suggestions as to what could be causing it if it's not dust clogging it? Any remedies I should try? Is it about to go pop?!