i was wondering that if you have 2 7900gt's which one would you use to connect to your LCD? is there a special type of cable wire that will connect both of them rather then one?
just make sure u have the bridge chip that (connects the 2 cards) connecting the 2 cards...this will physically make sli fully enabled
if your board is a retail board, then you should call the manufacter and request that they send you one, otherwise i dont believe you can buy them because for each model of motherboard the pci 16x slots are different lengths away....