This will not work. Both cards Must be more or less the same. Such as two 7900gs in sli or two 9800gt in sli or two gtx 560 in sli Not one 7600gs plus one 6800xt. Search around on the net and do some basic research before thinking this. <_<
^ +1. it will not going to happen. at OP: you should did your homework regarding the setup yourself. only asking question when it does not work as it should be