I recently updated my computer to Raid 0 and got a wierd problem with my second graphics card. First everything was working fine and after a reboot windows "found new hardware wizard" popped up. Tried installing the driver for the graphics card, but it won't work. I used driver sweeper to clean the comp from all drivers and installing the driver again, didn't help. I tried manually selecting the driver for the card, then windows shows it as the right card but it still has the yelllow triangle with a "!" before it. Without a driver for it windows only displays it as 3D video controller. I switched the graphic cards places and the bios starts beeping. Is my card broken or did i miss something here ? During the installation of raid 0 i didn't even touch the card and everything was working fine for an hour or two before the reboot. I have a EVGA 680 Sli mobo and running win xp with all the newest drivers.
Seems to me like one of your PCI Express slots might have died which is really common on that motherboard. Also could be that one of your 8800s died, which is also very common. Try both cards individually in both slots. Also XP does not have the best support for SLI, especially with the 8800/HD2900 series and up.