DesertOwl,
Here is the information that I posted on Sli in the forums some months ago. You will need Nvidia Inspector to get the benifit of this program and that is available as a free download. These settings are what I use and are a workaround for Sli until an official Sli is released by the developers. Alot have found that these work well for them while others do not. I have fps over London in the London Attack SP of 40---60fps with only minor stuttering when looking at the ground for navigation. My Sli is much weaker than your's so you should get realy good fps. Also use EVGA Precision tool which will give you fps, temps and % that both cards are using ( MSI also has a similar tool) these are free dowloads and will work with all Nvidia cards. Using this type of tool will indicate wether or not your Sli is working or not. If you find that one card or other is only running at idle temp (about 35--37 deg) then Sli is not working as it should.
Also see this post of mine, these are my basic Nvidia Inspector settings
http://forum.1cpublishing.eu/showthread.php?t=26236