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So, I recently tried to start up a computer of mine. It would not power on, so I replaced the PSU. When I powered it on, all the fans spun up and the POST beeps indicated a normal startup. The problem was there was no video output. Every couple of minutes, I hear the post code again. I think it is restarting after POST, but without video I have no idea why. Does anyone have an idea as to why this is happening, and how to fix it?

EDIT: The video card is a PCI-e card. There is no integrated graphics on the motherboard. If I remove the video card, the POST indicates a missing card. When I put it back, it goes back to normal, so I know that it recognizes that the card exists.

EDIT AGAIN: The monitor comes out of standby when I power the machine on. It also displays its menu fine, so I know the display isn't totally shot. Both the CPU and GPU fans spin up.

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Try pushing F8 and booting Windows in VGA mode? Maybe it's a video driver issue of some kind. – Chris S May 21 '10 at 23:29
up vote 1 down vote accepted

Try the following:

  • different monitor (one that's known to work on another computer)
  • different cable
  • different port on your graphics card (assuming your card has multiple outputs)
  • different graphics card

Does the monitor show a different message or different-colored light when the monitor is connected to the computer vs. when it's not connected?

Also, when you turn the computer on and off, does the monitor come out of standby?

If nothing else seems to work, double-check that your CPU and GPU fans are running, and that the CPU heatsink is properly installed. If the CPU overheats, it will automatically reboot or shut down, which could also explain why you keep hearing the motherboard POST.

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I added the information you asked for in a second edit. The CPU overheating is the only thing that makes sense right now but it shouldn't have a problem, as it was working fine a few weeks ago before the PSU failed. – Annath May 21 '10 at 23:23
Just wondering; did it turn out to be a heat issue? – rob May 26 '10 at 19:00
Try remoting into it from another pc on the network (Remote Desktop). If that works, then you know it is booting fine and it is a video issue. – skypecakes May 27 '10 at 18:12

You may want to try replacing the card.

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Disconnect everything, all the boards, hard drives whatever. Then start adding the peripherials one by one and boot every time you add a new device. As Zion said It could be a video card issue, so replacing just the PCI-e graphic card with another one would give you the answer, but this answer could be that you have a problem with the PCI-e bus instead of a mere card issue.

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