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My desktop just shut off and won't power back on.

  1. There was no warning or sounds, smells, or problems prior to the shut off.
  2. The computer seems to be still getting power, the front LED display is still active and this is powered directly from the motherboard.
  3. From my knowledge the only things that would prevent a computer from starting is a dead power supply, cpu or bad motherboard.

Any idea? I'm leaning towards a dead motherboard cause the fan should still power up if the motherboard is good.

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migrated from electronics.stackexchange.com Jan 15 '12 at 20:40

This question came from our site for electronics and electrical engineering professionals, students, and enthusiasts.

    
I assume you've tried unplugging the unit, waiting 5 minutes, and the plugging it back in? You might also want to try using the motherboard jumper to reset the BIOS. –  Daniel R Hicks Jan 15 '12 at 20:47
    
yes, i've left it unplug for over 30mins and nothing. I'll trying the BIOs jumper reset. As of right now it just seem dead. the fans don't event power up. –  acctman Jan 15 '12 at 21:08
    
Are there any beeps when you power it? –  Paul Jan 15 '12 at 21:19
    
no beeps, nothing. completely silent. –  acctman Jan 15 '12 at 22:00
    
I'm guessing the PS is bad. Dunno a good way to test the PS stand-alone, but you can at least try unplugging the drives and any other secondary loads to make sure one of those isn't shorting the PS. –  Daniel R Hicks Jan 16 '12 at 0:14

4 Answers 4

A system that is completely dead (nothing happens when the system is turned on) - would generally lead you to suspect a faulty power supply.

I'd be inclined to try swapping in a different power supply first, or if you were more technically-natured you can use a jumper on the ATX plug and use a digital multimeter to check it's output voltage. (Please use a guide and follow safety precautions etc.)

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I did the paper clip with fan power supply test. The power supply was able to power the fan. So would that leave the mboard and CPU as only possible faults? I should still get some response if the video and ram is remove right? Or are those two items required for the system to come to life? –  acctman Jan 16 '12 at 9:02

Try another power cord and a different wall socket, you never know it might be simple. If it is Not plugged directly into a wall socket, plug it directly to the wall socket, leave out any surge or battery backup if used.

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Tried a different cable and socket just now no luck. I think the power supply is still good because it's providing power to the front LCD display on it. Anything else I should try to narrow down the possibly problem? –  acctman Jan 16 '12 at 8:56
    
I tend to keep some spare parts, so my next step would be to inspect the motherboard for swollen capacitors, if they look good and perfectly flat on the tops, then I would install a known good power supply to see if that cures it, if not start disconnecting non essential items from the motherboard, leaving only 1 stick or ram, processor, graphics card (if it has on board graphics remove any add in graphics card and connect the monitor to the onboard video connector) and PSU, see if you get a post screen. –  Moab Jan 16 '12 at 18:18

I would suspect the PSU still as the most likely culprit - even though it may be able to power a fan this doesn't mean it can power a CPU properly. Get a PSU tester or swap the PSU out for a confirmed working unit to rule this possibility out first before you look at anything else.

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When your computer turns off with a blurry screen, does not turn back on but is getting power and every thing seems to be alright, and makes a beep sound when attempt to turn it back on but does not turn back on (it makes three beep sounds): it means that the computer has been used for too much of time and cannot work any more you should just wait till the next day or five hours and try again it should work if it makes three beeps sounds dont look inside your computer it may be very hot, so just wait it should work.

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