Since a few weeks ago, my PC started rebooting every time I play a game like Kings Quest (2015) and FF XV. Sometimes it's right when I start playing, other times it takes some time. If I then wait some time, I can play again for a little longer. When it reboots, I hear the "overheat beeping" and I get the "CPU was shutdown due to thermal event (overheating)" message.
Here you can check my PC's specs and temperatures while idle: click here, when monitoring temperatures while gaming, my CPU max temp was around 50ºC (GPU was around 82ºC) when I experienced the shutdown. Even so, I reapplied thermal paste on the CPU, to no avail: problem persists. The CPU's heatsink is a cooler master with one fan. My PC is very clean, too.
I performed stress tests with FurMark, both for CPU and GPU and had no issue.
Is the CPU really overheathing? Both CPU and mobo are quite old. Is it time for replacement?
I have a cheap PSU. Could it be the cause of this problem? I've been thinking about buying an EVGA 600w 80+B. I know it's not great but it's what I can afford.