I just replaced the thermal compound on mine today. It didn't want to start up properly afterwards but did eventually - now seems to back to normal. I had several weeks trying various remedies including a good clean out and adjusting the potentiometers. Try the easier stuff first then replace the thermal compound if all else fails. I found a good 35 step guide to stripping it down to the chips, cleaning off with alcohol and replacing with new compound. It takes a while but if you follow the guide carefully and put all the removed screws in some sort of order you can revive your PS3.