Motherboard LEDs on but no boot, faulty PSU or mobo?

thismafiaguy

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Jan 9, 2011
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I've been trying to get my new build to work for almost 2 weeks now. On my very first try, the system booted when I pushed the power switch on the case, and I was able to go through the UEFI and initiate Windows installation. But my system randomly lost power just minutes into Windows installation, and I was never able to boot the system again after that. I've tried using the "START" button on the motherboard to bypass the case switches, but got the same results.

I've RMA'd the power supply since then, but even with the new PSU, I still can't get the system to boot. I tested both PSUs via the paper clip method, and they both worked. I've tried booting with only the CPU, CPU cooler, and one stick of RAM, and then with only the CPU and the CPU cooler, which is a known working Corsair H80i from my previous build. I made sure to plug in all the power connections in the correct places and such, and there are no shorts as far as I can tell, I've tried booting with the motherboard outside the case on a box.

There is a clear CMOS button on the rear I/O instead of a jumper on the board, I've pushed that button numerous times, and the LED's would go off and come back on a second later, so I'd say clearing CMOS isn't the problem.

I'm fairly certain the the CPU isn't dead, because the system posted on my first attempt. There is the possibility that my CPU could have overheated and cooked itself in the 5 minutes that it was alive, but the fans on my radiator were running, the pump LED was on, and the pump speed was shown at ~2200RPM in the UEFI.

System Specs:
Intel i5-4670K
ASUS Maximus VI Impact Mini-ITX motherboard
Corsair Vengeance Pro 2x8GB 1600 DDR3
EVGA GTX 670 FTW
Silverstone ST55F-G 550W PSU
Samsung 830 128GB SSD
Seagate 750GB HDD
Fractal Design Node 304

I'm not ruling out the possibility that the replacement PSU could be faulty as well, but as it stands at the moment, there are other components that are much more likely to be at fault.
 

thismafiaguy

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Jan 9, 2011
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I've checked all the power connections on the motherboard and ensured that they are properly seated. I've even tried using two different sets of cables.

I have a modular power supply, so the cables are all detachable. Just to make sure, the 20+4pin connector goes to the motherboard, right? The other end of the cable has a single piece solid 24pin connector.

Out of curiousity, have you ever heard of any PSU and motherboard combinations that are incompatible due to less obvious reasons? And what are the chances of getting two defective PSUs in a row?