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My ASUS M2N-SLI motherboard would not turn back on after running fine for 5 years. Connected a new (still in the box) 430W 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 1000W power supply from it and connected to ASUS MB - same issue - light is on, fans bump over then stop. I disconnected everything from the MB and tested - same result. I tried again with 430W PS - turns on. I then put the original PS from ASUS M2N into my other machine to verify bad and the light was on, fans bumped over, NO boot or beeps.

Then I put the 1000W PS back into my other machine and now it is doing the same - light is on, fans bump over, no boot and no beeps. Disconnected everything from MB - same result. I ordered a new PS but now I'm concerned that the bad PS may have damaged the MB and the MB may damage the PS so that plugging the new PS into either will kill it too.

Why does system boot with older version power supply but not newer? Could a motherboard kill a power supply? I know the power supply could kill the board, 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 $1500 builds so I would appreciate helpful suggestions.

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Is your motherboard touching the chassis or are there spacers in between? – Rudolph Oct 14 '13 at 13:52
"The power supply doesn't have enough correct connections to use in this machine." So what did you leave out? That might be the troublemaker. – Bobby Oct 14 '13 at 14:18
MB is not touching chassis - has worked for 5 years. I didn't leave anything out - I only used the other power supply to test the MB and RAM; video complained because no power. No integrated video to use but that is irrelevant as it won't even power on with/without video. Anything I "left out" would just beep an error - the 430W PS doesn't provide power to video but does everything else. System powers up with 430 even with ALL devices plugged in, just no video to see if Windows or HDD are working. – GeneM Oct 14 '13 at 16:04
The question I'm asking is why it won't power up with a proper power supply and could it have damaged the PS from my other working system - which is now also NOT working and having the same problem, so two PS down now. – GeneM Oct 14 '13 at 16:08

This motherboard won't work without both the main power connector and the 4-pin auxiliary connector that is seen on the right, near the top; what you describe is a typical symptom of not having the 4-pin connector inserted, or having it in an incorrect orientation.

enter image description here

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