I have some trouble with my sli .
Sometimes when i update the drivers, It stop working just show Physx in Nvidia Controll panel
I know most of you already know this but the majority of the people dont know this . I have look in the forums for Nvidia and it is hard to find any info on this so here is a link to a program that will enable sli :http://www.techpowerup.com/forums/showthread.php?t=60844&page=217
And the post is#5412 Slipatch 1.42