Dell XPS 630i - can't find a new video card

I have a 2008 Dell XPS 630i and I can't find a new video card for it. I had a nvidia 8800 in it, but it's given up the ghost.


I tried 2 nvidia replacement cards, a 9800 and a 460. I didn't have the correct power supply plugs for the 460, and when I later tried a 9800, there was no screen and the computer just when beep, beep, beep, etc.

So I tried a Radeon HD 4650 and that seems to work but after a short while gaming, some sort of a video problem will occur, and I have to reboot my machine to get it to work for a little while.

I'm wondering if all of this is because of the wonky motherboard the old Dell 630i had. Anyone know if there is a video card available that works in an old XPS 630s?