Motherboard or Power Supply Failure?

G

gregory

n00b
Joined
Jan 30, 2007
Messages
35
Last night my computer started powering off on its own.

I ended up pulling everything from the case. I reseated the CPU/heatsink. Removed all but one DIMM of RAM in slot 1. I ended up reinserting the graphics card(there is no onboard video, I wanted to see if POST would complete). The power supply is connected to the main, CPU, and GPU. The only other connections are the CPU heatsink fan, and the lead from the case's power button. I've cleared the CMOS.

So it goes like this:

1)First power on succeeds. Onboard LEDs show a completed POST.
2)Machine powers off itself, typically after 3-5 minutes.
3)Power returns after a second, however the motherboard does not go through POST again. LEDs show a completed POST instantly. The CPU fan doesn't throttle back like normal.
4)Manually power off the machine. It doesn't power off itself again.
5)Second power on does not go through the POST process. LEDs show a completed POST instantly. The CPU fan doesn't throttle back like normal.
6)Manually power off the machine.

If I manually power off the machine before it has a chance to do so itself, I can then power on the machine and POST will complete its steps as normal.
If I wait until the machine powers off itself, the only way that POST will go through its motions again is if 1)I switch off/then on, the power supply, or 2)I wait a few minutes before attempting to power on the machine.

What think? Is this the motherboard or the power supply?

Any help is appreciated.

MSI P35 Platinum
Intel Core2 Duo E6750
OCZ 700W Power Supply
MSI Nvidia 8800gt
 
Maybe a combination of both:
1) The motherboard could be damaged due to the crappy PSU
2) Your crappy PSU.

Can you try a different PSU? Also, you did connect the 4Pin CPU connector right?
 
I take it you dislike OCZ PSUs. Unfortunately I do not have another PSU to test with. The CPU connector is correctly inserted.

Thanks.
 
With mysteries like this it helps to have parts to swap. Do you have a lower powered video card to try? Will it post with the video card removed? Disconnect the motherboard and connect as many things as you can to the power supply then force it on. Load the power supply with 6 fans, 4 hard drives, 3 optical drives, and anything else you can plug in and see if it stays on. Got a multimeter to measure the voltages? Does the motherboard have any funny smells? Anything look burnt or burst? Motherboards have surface mount resettable fuses, it could be that some component somewhere failed causing that stage to send too much current.

I've had Benny Hill stuff like this happen to me with an OCZ power supply...
 
No spare video card either. Without the card, POST halts where it should at initializing the video interface. No multimeter or funny smells, nothing looks off. I tried green+black jumping the PSU with two case fans and an old hard drive. It didn't work, although it tried. I was uncertain whether I had created enough pull to get it going. I'll try throwing some more items into the mix.
 
It sounds like you might not have enough resources to repair this on your own. Time to buy replacements. :) A this and that here and there and you can do more involved troubleshooting with more systems. Start with a new power supply, no one can ever have too many of those; I have I think 17.
 
Ordered a Corsair HX750. 7 year warranty and 80 PLUS Gold. Fingers crossed. If that's not it, I just might fix the whole thing with a hammer.
 
Happened to me before. After 2 days of diagnostics, it turned out to be bad video card. Put a new card in and back to normal operation.
 
...and we have a winner. It was the PSU. These things seem to fail more often than any other component. Rant, rant, rant. Anywho, thanks for the help. :)
 
Called it! :D

Oh and to answer your earlier question: I dislike OCZ products in general due to OCZ's shadiness. However the OCZ PSU you have was more than likely the GameXStream, a PSU well known for low quality, due to the age of the rest of the system. Hence why I called your OCZ PSU a crappy PSU.

Anyway good to see that your problem was fixed.
 
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