I have notebook Alienware m17xr2 and 2 680m in sli.
I can't include sli in settings of the video driver, there
in general there is no such function.
I know that the same problem in m17xr2+580m sli was solved by installation of a patch of HyperSLI_0.7_beta and M17x-R2 Modified SLI Drivers.
You can find also for me the solution of this problem?