Question Most Unusual PC Failure

Dec 21, 2019
While using my desktop PC it suddenly powered off. Not a Windows shutdown but a power off as if someone pulled the power plug. I tested the power supply and found that it was dead. No voltage output. I grabbed a spare I had and found it too didn't work. I tested it and again zero output voltages.

I purchased a new power supply. Installed it and to my utter disappointment the system would not power on. I tested the new power supply and found it was putting out correct voltage. In order to test the power supply if not installed you must connect the black and green leads on the large multi-pin connector on the power supply. The green and black wires are the power supply turn on connections. IMPORTANT! Obviously, if you try this you must make sure that the power supply is NOT connected to the mother board.

So, I must conclude that the mother board is bad also. I find it very odd that both the power supply and the motherboard would be bad. Maybe the power supply, as it died, did something that fried my motherboard? I sure hope it didn't fry my CPU chip! (By the way, the new power supply still works after plugging it into my bad motherboard.) Very odd that both the power supply and motherboard would be dead simultaneously.

Has anyone experienced this? Anyone have any ideas or info on how both could be bad seemingly occurring all at once simultaneously?