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No video signal when agp graphics card hooked up tp PSU

  • Homebuilt
  • Systems
Last response: in Systems
September 6, 2010 5:26:53 PM


My problem is that when i connect the 4-pin molex connector to the video card i get no video signal (black screen when computer is turned on). However, when i DON'T connect the molex connector everything seems to be ok. How can this be possible?

MB: Asrock K8upgrade-NF3 (
GPU: Club3D Geforce 6600 256mb AGP (nVidia Corporation NV43 [GeForce 6600] (rev a2))
CPU: AMD Athlon64 3000+
RAM: 1.5GB pc3200 ddr sdram
PSU: 350W

It was previously running on an Epox motherboard until i replaced it but the problem still remained. I also had a Chieftec 450W PSU but it started causing system instability (found memory errors with memtest86+) but switching the PSU made no difference either, The one i'm using now came actually with my computer case (dated way back). I have tried reseating the video card several times, also resetting CMOS and loading bios defaults. Nothing. I pretty much assume that it's some kind of an issue with the video card but can somebody explain how my system can work with the 4-pin molex connector disconnected from the PSU?

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September 6, 2010 5:59:49 PM

try the video card in another pc if thats not it its your board
October 29, 2011 2:40:54 AM

Mine has the same error. It stopped sending a signal to the VDU. If I disconnect the power supply molex connector it works again (on a reboot) with the fan still coming on.
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November 2, 2011 2:44:30 AM

Just to make it clear, the molex you're using on the GPU is not a flat inline four pin molex, I believe it should be a 6 or 8 pin power connector. Also Restart it and go into the BIOS and make sure it's set to use the video card and not the on-board video first. Should be set to PCIe/VGA first, then the on-board AGP if no PCIe/AGP detected.
November 2, 2011 2:48:55 AM

Power down the computer, plug in the video card power, unplug your video cable from the on-board video and plug it into the video card, start the computer making sure the BIOS is set to use the video card first and the on-board video second and hopefully that will solve your problem.