My ASUS M2N-SLI motherboard would not turn back on after running fine for five years. I connected a new (still in the box) 430 W power supply - ATX 2.1 - the system powers on. The power supply doesn't have enough correct connections to use in this machine.
I shut down my other PC and took the 1000 W power supply from it and connected to the ASUS motherboard - same issue - light is on, fans bump over then stop. I disconnected everything from the motherboard and tested - same result. I tried again with the 430 W power supply - it turns on. I then put the original power supply from the ASUS M2N into my other machine to verify bad and the light was on, fans bumped over, and NO boot or beeps.
Then I put the 1000 W PS back into my other machine and now it is doing the same - light is on, fans bump over, no boot and no beeps. I disconnected everything from the motherboard - same result. I ordered a new power supply, but now I'm concerned that the bad power supply may have damaged the motherboard and the motherboard may damage the power supply so that plugging the new power supply into either will kill it too.
Why does the system boot with an older-version power supply, but not newer? Could a motherboard kill a power supply? I know the power supply could kill the board, and that's why I already ordered a new power supply.
Any ideas I might not have thought of? It's bad timing to have to replace two USD$1500 builds, so I would appreciate helpful suggestions.