Well I just bought my self a used XFX 4890. Old I know, but it was a huge upgrade from what I had previously been running, an 8800 GS. Anyway, I installed the card, no problems. Booted up and installed the correct drivers, no problems. The fan starts rattling, I left it for now. Put it to sleep, and next time it comes on it's fine. Same thing for the next four sleeps. Then it starts rattling again, I turn the computer off, and take it out to see if something is stuck in the fan or if it's rubbing against something. Nothing. Put it back in and now windows just sits on the "Starting Windows" screen.
I think my PSU is adequate for it, I had used it in a game for a couple of hours without issue.