Quad SLI is just a show-off thing
 

Even at Nvidia's press conference the senior Nvidia chap said, "If you are crazy enough, you can buy two of those displays," and he was referring to 30-inch Dells. He talked about the ability of 7900 GTX and GT to do dual, dual DVI support. Yes you have to use dual word twice. You have to hand it to a company that wants to sell you four graphic cards for gaming.