Hi TomW,
I've been searching for over an hour now about how to users did a replace/ upgrade on their video card. Sorry about your trouble, looks like were in the same boat.
had a meager GT430 installed on the PCI-E slot 1 of my 990FXA UD5, which I then replaced with a HD6670. Upon power up, letters and numbers (ala Matrix) started floating on the screen which Im certain means trouble.
How do you perform an upgrade on a video card anyway? I suspect, I should NOT have remove the GT430 and instead added the 2nd card (HD6670) and then allowed the BIOS to recognize it. Is that correct?