Post your setup please
Maybe, but just maybe it could be CPU throttling that's giving you "lag"? Assuming we're talking FPS drop? Is it intermittent or consistent fps drop?
When I played the beta I had my Hyper Threading, C States and Speed Step disabled to make sure my CPU wasn't throttling, I'm using a tri-SLI setup as well so for your problem that's the first thing that just comes to my mind, although I hadn't tried when I played with CPU Throttling going on.