Mac Pro 1,1 no longer working with 6870?
I've been using a 6870 in my Mac Pro 1,1 for over 6 months now with virtually no issues (some minor artifacting a few times). Earlier this week, the Mac Pro would no longer display any video. Display works fine, as I've tested it with a Mini. I tried connecting a different display to the Mac Pro, still no video. I've tried removing RAM, resetting SMC, PRAM, etc....
The Mac Pro chimes, boots up fine, keyboard responds. Only issue I can find is with the lack of video.
I tested it with another brand new 6870, and still no video.
I thought perhaps I downloaded some kind of Apple update that affected the 6870 working with it, but I can't seem to find anyone else with this issue on the forums. Thanks for any advice/help.
BTW, I've also tried booting from a drive with Snow Leopard as well as powering on with no drives installed to see if I could get the flashing folder. Still no video of any kind.
Mac Pro, Mac OS X (10.7.3)