Quote Originally Posted by $oul
I have this same problem, i rma'ed my 3d card still waiting for new one.
But you now say it couldn't be the card, i hope it isn't the board

What bios are you using ? Do you have artifacts in windows safe mode ?
I only had artifacts in POST and in windows nothing but once i installed drivers i got black screen.
I have a 7950GX2.
Mine also booted while there was no plug from the psu connected to the 3d card, didn't even gave a warning about that.

I have seen other people with this problem and say its because memory of the 3d card is broken?

This sounds to me like the nasty PEG LINK mode option in the BIOS is affecting these cards even before any serious 3D Function calls are being made.
If you don't already know - PEG LINK is feature on nearly all boards, just called different things by different vendors, but it overclocks the card at boot-up and its handled by the motherboard. It handles nVidia and ATI cards differently. In my experience, it's never been a good thing. If you're running the "entire" system at stock/default levels - sure it can help. But, who the heck does that? Go into the BIOS and turn that nasty PEG LINK mode to NORMAL and see how things go then.