Instead of analyzing your testing methodology, let's roll back to troubleshooting your actual problem.
What are the "PSU issues" you're experiencing and what makes them "PSU issues"?
My computer has no fan spin and will not post when I press the power button, I have tried breadboarding and this does not solve the problem, the orange motherboard power indicator is on as usual when the PSU is switched off from the back but plugged in. This has happened multiple times, when it happens, it usually takes a few days and then it starts working perfectly normally again for a while and the cycle repeats, this has happened 6 times.
Sometimes the time is not correct when it boots again so I have changed the CMOS battery, which has not fixed the problem. There is no fan spin at all not even in the PSU but there is fan spin in the PSU when I test it with a paper clip in the motherboard power connector.
I am not 100% sure but when I strain it with heavier loads like gaming, it seems to stop working although it might be a coincidence since I have only noticed this recently.
Whenever this happens I had turned off the computer the night before and it does not turn on in the morning, it has not crashed whilst it has been running or stopped working after short amounts of time of being shut down either.