I seem to be having issues with the third PCIex16 slot on the board. Last weekend I started having issues getting tri-sli enabled kept getting unknown VGA adapter errors. After some testing and moving cards around it appears the third slot is dead on this board. Device manager only shows 2 gtx 280 while three are installed all cards work fine in the top or middle slot single or SLI. No cards work in the third slot single dual sli or tri-sli. Anyone have any ideas I can try before RMA. I have already completed a clean install of both vista 64 and XP 32.

Thanks