Windows 7: Video not working without system RAM full? Really need some ideas...

I have a weird problem. I have used a Verto 9600GSO in a custom ASUS build without too many issues, but the other day I lost one of my two sticks of system RAM and now the video card isn't seen in the device manager. I can get video from the onboard video port, but nothing from the video card. The worst part is that I know the 9600GSO is in good working order as it worked flawlessly on another system, and another card worked as expected in this system. Why does it seem that my aftermarket 9600GSO doesn't want to work without both sticks of RAM?

Is there anyone out there who can give me some input here?

Have you tried resetting the bios?
The device manager can sometimes get stuck on stupid and tripping the bios should put it on a new irq allowing the device manager to re-detect easier.

I cleared the CMOS, updated my BIOS, cleaned all of the contacts....I even took each component separately to a nearly identical computer to test every component, and aside from one of the two 4GB sticks of RAM I have turned out flawlessly.

My worry now is that the RAM failure might mean that my motherboard is a dual-channel ONLY RAM board that I somehow "tricked" in to seeing a single stick of a dedicated pair of RAM sticks. Actually, that's not so much a worry as it is a headache. If I got it to work ACCIDENTALLY...I'll never figure out what I did to get it to this point and go back to the original specs.

I REALLY appreciate the input.