My Playstation 4 would run very loud and eventually overheat, to the point of the machine turning off. The fan was literally breaking down, it was so worn down that when you blew into it with your breath, it wouldn't even turn on it's own.
I replaced the fan, and the PS4 was quite but was still overheating. Replacing the worn down fan didn't really solve the problem in its entirety. as there were other factors to deal with.
So after replacing the fan, I dusted the PS4, it was really freaking dirty in there. The heat sync was a disgrace, full of dust. I remove the dust, the PS4 was STILL overheating. Then I decided to re apply thermal paste to the CPU. PS4 was STILLLL overheating.
At this point I was close to giving up and buying a new system....but then I also noticed that the thermal pads where not placed properly under the metal guard that covers the motherboard...these thermal pads were sitting on the RAM chips, rather than on the metal protrusions from the metal guard. Once the thermal pads were moved from the RAM chips over to the metal protrusion, the PS4 was finally working properly.
Some of the thermal pads were breaking apart, so when I would put them on the metal bumps, I'd fill the cracks of the thermal pads with thermal paste. It's been nearly two weeks and it runs quiet and hasn't overheated since.