Make sure that SLI is actually active (if you use the express update it won't be after updating). Then make sure you have created a custom profile for AHbeta, and that the SLI method is set to "Force alternate frame rendering 2."
I am fairly certain that SLI is working, both from the display tool shown when alternate rendering is forced, and by the difference in fps when enabling and disabling.However, strangely today the framerates were a good bit higher. Nothing new on my end that I can imagine.