I've tested a couple things in multiple games. Battlefield 3 one of the main ones, Also Batman Arkham City. Battlefield 3 being preset to High Settings which my single gtx 460 handles a lot better than my SLI setup. I get more consistent FPS with a single gtx 460 than I would with them in SLI. When running the 460's in SLI my fps dips below 30fps sometimes.
Also noticed when running evga (on screen display) sometimes my cards sit at 30% usage. And whenever they feel like it they bump up to 70% plus and give me very nice frame rate.