Hello,
in the past month I had a loud fan bearing, it was pretty random when it would start and stop being loud, in the last few days the loud noise would only start few hours after I turn on the system (it doesn't make difference if the PC idles or being used on 90%) and would be noisy for ~6 hours but weirdly, sometimes it goes silent for a few minutes. Last night I was watching a movie, I could hear the fan switching from noisy to quiet quickly, like the bearing catches the right pace (or I don't know how to say it in english) so it would be quiet. Then after an hour of sweet silence the PC shut down. I couldn't turn it on right after it shut down, so I was kind of sure it was overheating, because it was the same behavior when my GPU overheated on demanding games. I waited some time and turned it on again, and after a few minutes it turned off again. I called it a day and finished the movie on my phone. This morning I turned my PC on, it was doing fine for 1-2 hours, the fan was not noisy at all, then the PC shut down again, right after I plugged my usb headset, for a moment I though it was short circuit, but it was just a weird timing, because when I turned the PC on again with only power connected, it turned off in a few minutes.
In that 1-2 hours I downloaded hwmonitor, all the fans I could check were working, except for the GPU fan that would only start at 60°C, but that's normal. Temperatures were fine during the whole time. I couldn't see the PSU fan in the program, so I checked it myself, it was woking too.
I don't know which fan was being loud, I suspect the PSU, but I can't know that, because there are many fans in the case.
Also, I can't hear the bearing anymore, but I don't know if it's because the PC shut downs before it could start, or it's because the bearing gave up.
I think the PSU is overheating, because I can't see its temperature while everything else in the PC was normal temperature-wise, but I'm not sure and I don't want to spend money on a better quality PSU just to have it turn out it wasn't the PSU which caused the problem.
Some help/advice would be appreciated.
edit: the problem was indeed the PSU, works fine since replacement