There are similar questions on this site, some do not have definitive answers while in other cases it was the motherboard that was faulty or overheating issues. In my case it’s the PSU.
The purpose of this question is to take further deep insight into the way ATX Board & PSU work together.
Within 25 – 30 minutes of starting, PC just shuts off as if power button is pressed. It’s an old PC with Socket 754 board and AMD Sempron CPU.
I eliminated the following and below is the necessary information
There was no overheating. Temperature never crossed 40 C (104 F)
Motherboard was not faulty. This issue did not occur with another PSU. With healthy PSU, system ran continuously for 3 hours and I tested it 4 more times for that much long duration
PSU in question was 450W ATX SMPS. Not from international brands like Cooler Master or Corsair or so.
All HDD, DVD removed, system was just at BIOS and nothing more
Once abruptly shut down, it would fail to start again for at least 15 – 20 minutes
PSU fan spins well when it starts
Obviously as mentioned earlier, I have nailed it down to faulty PSU. However the same problematic PSU in paperclip test passes and using my DMM I have checked all voltages they are just good for over an hour.
What are the reasons that the system shuts down under this scenario. Could it be that the…
PSU loses PowerOK after sometime under load?
Voltages fluctuates beyond what is tolerance stated by ATX specs, under load but not when only fan is connected and no motherboard?
Anything to do with temperature within PSU?
Further, what is that integration of ATX board and ATX PSU that results into this behavior i.e. abrupt shutdown of PSU?