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PSU does not turn on when PCI Express power connected

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August 1, 2009 1:14:04 AM

Last night I was just using my computer as usual and suddenly it turned off. Attempts to turn it back on would result in the power supply flashing and spinning half a rotation, yet the power button light on the front stayed on. This light could be turned off by holding the button (as you would to turn off the whole computer). I was not able to get the computer to turn on at all last night.

After work today I picked up a new power supply (Thermaltake 450W) from the store and installed it in the computer. I connected it to the motherboard, hard drive, and graphics card (Zotac 9800GT). Same exact problem. I removed the power connector from the graphics card (6 pin PCIe) and tried again. Success!!!! I pulled out the graphics card, cleaned it up, and re-seated it. No good...same problem. Is there any chance this could be a motherboard issue, or is the card just done for? It was only about a year old. Any ideas?

Unfortunately I cannot do any further testing right now, because suddenly booting into Windows XP will cause a BSOD almost immediately. The error is Unmountable Boot Volume, presumably caused by the constantly turning the PC on and off. I'm hoping to find my Windows XP CD soon so that I can get into the recovery console and get this fixed....But could this be an indication that the problem is actually the motherboard and continuing to troubleshoot is risking other components? My windows hard drive has some stuff that would *really* suck to lose, so I'm already getting nervous.

Any ideas, thoughts, recommendations - all would be greatly appreciated! Thank you so much in advance!!
a c 113 B Homebuilt system
August 1, 2009 2:21:41 AM

Please give a full parts list when asking for help.

Are you saying you can boot with graphics when the PCI-E power connector is left out?
August 1, 2009 4:22:05 AM

Foxconn C51GU01 Motherboard
AMD Athlon 3800+ Processor
2GB DDR Ram (4x 512MB)
Thermaltake Black Widow 450W PSU
Zotac 9800GT+ (PCI-E)

Honestly the rest doesn't matter too much, as the problem continues with these components disconnected (SATA, IDE Drive, Sound Card).

What you said is correct - if I leave my graphics card in the PCI-E slot, but have the 6 pin power connector disconnected the computer turns on just fine. It's just whenever I apply the power connector to the graphics card that nothing turns on. I found my Windows XP CD and have it running now...but still won't work with the power connected to the graphics card. Did the card fail or get shorted out?

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August 1, 2009 4:24:08 AM

Just to clarify, the graphics card will *not* even power on without the 6 pin connector. When this is removed the computer works fine if I use onboard graphics.
August 1, 2009 4:43:00 AM

I thinking you have found the problem.
August 1, 2009 4:54:36 AM

If your onboard graphic adapter is working, your graphic cards is probably the problem. Try reinstalling all your graphic drivers. Uninstall your card, the drivers (use Driver Sweeper), reinstall the card... and if you can, the drivers.

If the same thing happens, it will be hardware related. It could be your graphic card, or your PCIe slot on your motherboard. Either way, it will cost you 75$.
August 1, 2009 5:08:44 AM

Had the same issue 2 weeks ago with a brand new 9800GT. Turned out the card went bad. I made the same mistake of new PSU first also.
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