Question Heat issues: CPU overheating even with AIO cooling ?

Nov 29, 2022
Hello everyone, I want to consult something that has me quite intrigued because I can't find any relevant information about:

A friend has a desk PC with an AMD Ryzen 5 CPU which he took to technical service for a liquid cooling installation, everything was working well for arround 2 months until some days ago, the PC started with the sudden shutdowns so he called me looking for some help. After a couple of checks, i realized that the CPU temperature was going straight up to 80-95 ºC without any charge but the bios interface, i started with the dissasemble of the computer and the cooling system looking for some clues about what was going on and realized that who installed the AIO Cooling forgot to remove the plastic cover on the copper foil, they even applied the thermal paste but the plastic cover was basically isolating the refrigeration.

I removed the plastic cover and did the propper installation again with thermal paste and it started to work well, suddend shutdowns were gone and iddle temperatures were around 40-45ºC and on stress tests around 70-75ºC but only for two days, today it started with the sudden shutdowns again, so he took the PC back to the techinal service who installed the cooling and the dude just reinstalled it with thermal paste again got it working again with 40-45ºC iddle and 70-75ºC on stress tests... Now that we are at home, the iddle temperature again rounds 60ºC.

I dont think that the AIO cooling is the problem, because it's working, the radiator gets warm, fans working at the max, the pump is on, and it's new (bought it 2 months ago as i said)
I dont think that the motherboard is the problem, seems like the CPU is getting the normal tensions

During the tests, for curiosity I disconnected the liquid cooling from the current and completely removed it from the CPU and the machine did not even managed to show video, so i think that the CPU temp is going up too fast that it restarts the PC before it could even load the bios.

My question on this point is: Can a CPU actually get damaged for being exposed to high temperatures for long time making it warm even faster than it should normally? My friend is a graphic and 3D designer, so you can imagine the load that his PC handled during these two months being poorly refrigerated.

It would be great to hear expert opinions.