PC randomly hard resets

[KrypticASFK]

So my pc starting randomly hard reseting while im playing games, so i thought it was the cpu overheating so i replaced the thermal paste since i havent before, however nothing changed it started to occur more frequently and i made sure to push down all the plugs to make sure they were in properly still nothing, im thinking its the power supply but i cant tell and the cpu doesnt have a thermal monitor so i cant tell my cpu temps either, my gpu temps are perfect.. after the hard reset my fps is so low, so im thinking thermal throttling but can this still be diagnosed with a faulty powersupply? If so is there any stress test to see if it really is the power supply? ive tried a stress test on the cpu and the gpu it didnt crash or overheat so im out of ideas  please if you got any idea let me know

[SimplyGone]

PSU