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I have an old Windows XP desktop that decided to die a little while back when the machine was rebooted following a Windows update. During shutdown for reboot the PSU powered off and will not power on again. Press the power button and the fans spin briefly but nothing else happens. No power, no beeps, nothing. Disconnected all hardware, except motherboard & PSU, still nothing.

I put in a replacement PSU, and the computer boots up fine, and runs Windows no problem. Another update came in and it requested a reboot. Again during shutdown, the PSU powered off and is now dead in exactly the same way. Different model and brand PSU.

I've followed the PSU instructions about overload/shorting issues, i.e. by disconnecting mains power, wait a few minutes, reconnect and try powering on, but nothing.

I have also tried a further PSU but only going as far as the BIOS screen. This works fine, and is not harmed if I manually shut the computer down by holding in the power switch. I don't want to let it boot into Windows in case it is also killed though.

I've gone through all the cables to ensure they are not damaged and connected fine, and checked for anything that may be shorting out. Also, when this initially happened there were no hardware changes. This desktop has been running fine for years without changes made to it.

Has anyone heard of something like this before and what it could be? I suspect something is shorting during power down (disc spin down perhaps?).

I can provide a full PC spec if needed, but have left it out to avoid clutter for now.

It's an old PC and I intend to just replace it anyway, but I want to re-use the discs at least briefly to transfer data and concerned that a drive might be frying the PSU. Unless anyone has other ideas?

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migrated from Mar 23 '11 at 15:17

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Without creating a long-winded answer, the issue is NOT the software. When Windows finally shuts down, it triggers the PSU to turn off the same way every other operating system does, or it wouldn't work. – Breakthrough Mar 23 '11 at 15:54
That's my thinking too. Just a question of what bit of hardware is the problem. – tjmoore Mar 23 '11 at 17:11
One other concern I've got when I get my replacement PC is could this be caused by the power strip I have? It's a Belkin strip of some sort as I remember. Fairly modern and I don't think there's any problem with it (UK power strip, so fused, as are all the plugs). Just wondering if some fault in the strip could be killing the PSU, but doesn't make sense it's only on shut down and especially as the PSU still has power from the main when the PC shuts down. – tjmoore May 12 '11 at 10:21

I'd point the finger at your motherboard first, since that's the most intricate thing directly connected to your PSU.

Without a doubt, it is not a software problem.

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Agreed. Main thing I want to rule out now is the discs, as I want to re-use them but don't want to kill the PSU in any new PC I put them in. I could put them in an external caddy though to transfer data off. – tjmoore Mar 23 '11 at 19:15

Instead of only disconecting main power, wait and turn on, try the following:

  • remove power cable from the wall
  • try to turn on several times the computer (looks dumb but will discharge capacitors mainly and maybe some static)
  • plug power cable again
  • start computer.
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I've done all except the turn on several times. I'll give it a go, although the previous PSU had been left disconnected for a month and still doesn't work. I'd suspect a fuse gone internally, but both PSU claim they have protection circuits and just trip something inside which supposedly will reset. – tjmoore Mar 23 '11 at 19:14

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