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Video Card or PCIe slot problem

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New Member
May 24, 2010
I put together a budget system with an old motherboard for my son to use for gaming and schoolwork in college. We had it running fine down here for a year with no problems. Then last month I shipped it up to him in the original box that the tower (case) came in with the styrofoam pads and all. When he got it, it wouldn't POST. No video or BIOS. I don't remember if he said that he was getting diagnostics beeps at that time. But he checked the RAM one stick at a time, wiggled cables and removed, re-inserted power plugs and such.

So I sent him an old Radeon VT 4350 PCIE 512MB video card that I had. And it booted off of this card. This is a very small cheap card with no extra VGA power ports from the PSU. The card that he was running was a Radeon 6950, that needs the VGA power from the PSU. So I bought him an XFX Radeon RX 580 from Amazon. He plugged this in and again no POST. At this time he is familiar with the beep codes and is getting one long beep indicating "no video card".

He noted that there is a red LED on the new GPU that comes on when plugged into the PCIe slot and a blue LED that is on when the VGA connector is plugged into the card. I sent him a cheap PSU tester that said it looked good but I don't know if it reads all three +12 volt power pin-outs on the VGA cable from the PSU. So I have sent him a multi-meter so he can read all the VGA pin-outs under load and see if it looks funny. He'll get this Monday.

Here are the current Specs:

Motherboard: GIGABYTE GA-870A-UD3

CPU: AMD Phenom II X4 955 Black Edition 3.2GHz AM3

PSU: EVGA SuperNOVA 650 G1, 80+ GOLD 650W


GPU: XFX AMD Radeon HD 6950

RAM: CORSAIR Vengeance 8GB (2 x 4GB)

OS: Window 10/64

So, if the multi-meter read good on the GVA cable under load then it has to be the motherboard, right?
If the motherboard has integrated graphics it may be defaulting to that, and it may have failed. I would try going in the BIOS with the GPU that worked and make sure the default VGA is the graphics card slot, as well as make sure the heavier cards aren't dropping and screwing up the connection at the PCIe slot.
Thanks Alaric,
The 870A-UD3 (motherboard) has no IO on the back panel for video out. He tried loosening the card screws, lifting the card then tightening. That didn't help. I also had him move the video card to the lower PCIe slot (X16 x4) and that didn't help.
Good ideas though.
It's not the MB... You proved that with the cheap video card that did not require power. I would have him reconnect the VGA power cables on the PSU. I would also (if needed) have him switch to his 2nd set of VGA cables and plug them into VGA #3 & #4.
I don't know the video cards in question - BUT a red light could mean that it's not getting the required power to work.
My first guess would be the PSU not providing enough power to the video card. It it were the motherboard or the PCI-e slot then the low end card would not work either as it gets all it's power from the PCI-e bus. I would also try the two newer video cards a working computer to test their viability.
We used one of those cheap PSU testers and it checked out. Then He used a multi-meter on the PCIe/VGA cables plugged into the video card and it read 12.25v on all 3 rails. I'm thinking new MB, CPU and RAM.

What do you think?