Won't power-on after power failure

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techie52

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Sep 26, 2013
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I had a power outage at the office day before yesterday. The UPS kept my system running until I shut it down in an orderly way. I then turned the UPS off and (after managing several other systems and UPS's) went home.

The next day, everything came up fine except my PC. It would not respond to the power switch at all. No fans turning, disks spinning, POST, LEDs etc.

I tried it both connected to the UPS and to a known-good outlet. When I opened the case the standby light was on.

I tried disconnecting the power switch and shorting the pins, but that didn't work either. I messed around with the power cables etc. but it was clear they were OK. Finally, after an hour or so, I pushed the power button again and my system started up like normal.

Does anyone have a clue what the problem was? I need a stable system so I'm inclined to replace it unless I can figure out what went wrong. My system is:

Antec P150 / Earthwatts 430
Intel DZ68DB / onboard video
Core I5 2500K
16GB whatever cheapest good brand RAM
Crucial M4 60GB + 1.5TB HDD

I'm posting this in Motherboards because I can't imagine what other component could be responsible. I would appreciate any ideas about the cause of this problem.
 
Solution
getochkn
Sounds like the MB and I have a stack of motherboards that are flaky like that. It's something in the startup circuit or the caps related to it. Once the caps get energized enough, it will turn on. I have a few PC's around my place that are gerry-rigged by jumping the green/black psu wires all the time and leaving it like, then when power is applied, the system lights and fans turn on but still not full power. then I have to push the power button to get full-full power out of it and it actually turn on.
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getochkn

getochkn

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Jul 2, 2006
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Sounds like the MB and I have a stack of motherboards that are flaky like that. It's something in the startup circuit or the caps related to it. Once the caps get energized enough, it will turn on. I have a few PC's around my place that are gerry-rigged by jumping the green/black psu wires all the time and leaving it like, then when power is applied, the system lights and fans turn on but still not full power. then I have to push the power button to get full-full power out of it and it actually turn on.
 
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Solution
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techie52

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Sep 26, 2013
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Thanks getochkn, that sounds logical. Now I have to decide whether to replace the MB or the whole shebang. A faster CPU would be nice for the occasional video editing I do, but Haswell doesn't seem like a huge leap. Hmm.
 
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techie52

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Sep 26, 2013
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Follow-up: Intel has agreed to replace the motherboard under warranty. It's costing me $25 for express cross-shipping. Thanks again, getochkn, your answer helped me convince the Intel tech.
 
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techie52

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Sep 26, 2013
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Followup 2: It wasn't the motherboard after all. The replacement showed the exact same problem - too much of a coincidence. I took apart a different PC and put the replacement motherboard in its case, plugged in the power connectors and shorted the switch pins = success!

So now I'm back up and working in the other PC's case. The problem could be the old power supply or something in the old case shorting something on the MB.
 
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