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Probably a lost cause, but I thought I'd ask before I start replacing hardware.

I have a desktop that's been boxed up for a while, and when I set it back up I wasn't getting any video output. I pulled out the PCIE card and cleared the CMOS, then it started working fine with the onboard GPU. I assumed the card was bad, since I had problems with that model in the past. Then after a day or two the system locked up and I had to do a hard shutdown. Now I'm not getting any video from the onboard either. I cleared CMOS again, tried with and without the card in place, nothing. When I power up the CPU fan spins, but I don't see any other signs of life. The hard drive access light doesn't seem to come on either, which makes me think that this is not just a video problem, but I'm not sure what BIOS does if it can't detect any video device.

EDIT: Interesting development. At Xantec's suggestion I disconnected everything, which worked. I then started reassembling it piece by piece, and I now have everything back together- even the video card and other peripherals that were not attached before- and it's working fine. I'm typing from it right now. I have no idea what the problem could have been, but since I didn't narrow it down to anything I'm afraid it will just happen again.

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are there any POST beeps? do you have any spare RAM or, on the outside chance, a spare CPU that you can test in it? Have you tried removing all other devices connected to the motherboard (example: HDD, CD/DVD etc)? –  Xantec Nov 2 '10 at 19:57
    
I don't remember any beeps but I really wasn't listening. No spares. I removed all peripheral devices except for the HDD and DVD (both SATA, if that matters). I'll try removing those and listen for beeps. –  Travis Christian Nov 2 '10 at 20:05
    
Could be a bad PSU also. You might consider posting your Make and specific model of PC –  Moab Nov 2 '10 at 21:03
    
Unplugged absolutely everything except for CPU RAM and power, and we're back! Now to find the offending device... –  Travis Christian Nov 2 '10 at 23:11
    
Well, it's all back together and still working. See edit. I'm pleasantly confused... –  Travis Christian Nov 3 '10 at 3:22

3 Answers 3

Any lights on in the motherboard? This is probably either a failing motherboard or failing power supply (I wouldn't throw that video card out yet!). I suspect it is a failing power supply as it couldn't power the card by itself, then when you took some load off of it, it eventually couldn't provide enough power to the motherboard. Newer motherboards won't power on without sufficient power, but older ones might still power whatever they can.

I would hook a volt meter up to one of the power supply's rails and see what you get.

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unless you are confident in your ability with a volt meter I recommend getting a power supply tester. its a good weapon to have in your PC troubleshooting arsenal as it is quick and easy. PSU testers @ Newegg tinyurl.com/2b8wz5p –  Xantec Nov 3 '10 at 0:25

May be your main board got a short circuit inside.In most cases when we do a clean re installation of hardware, these issues will get solved.

At sometimes residual voltage will also cause this issue. to bypass residual voltage you have to hold the power button on CPU cabin for a minute and during this process do not plug the power cable to wall socket.

Another cause will be your power supply, when you install video card, ensure that you have installed a power supply with enough watts to power up the whole system.

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I have had the problem of power-supplies not generating enough power in the start-pulse to start the computer. They way of solving that was to remove the cables and rearrange them in the power-supply. It is entirely possible that is similar to your situation.

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