Tree:
A while ago u asked Luthier "is Sli supported?", Luthier answered: "of course it is, why wouldnt it be" (like asking if headphones is supported hence Luthiers answer)
So far so good, you got the answer to your question.
Now u are wondering why Sli isnt working like it should for everyone (not the same thing as: is Sli supported) and THAT is a question you have to ask NVidia (and AMD/Crossfire). The answer to that is: because none of the company's have made a profile specifically for Cliffs of Dover, simple as that.
It works with global settings but its not working as well as it could, again, because there are no profile specifically for CloD. Its the same with virtually all games until NVidia and AMD see fit to add a profile. It was the same with IL2 Sturmovik. Sli and Crossfire has only become popular in the last few years and there where never a profile from either company that enabled this for IL2 Sturmovik. There where ways to get it to work. i personally had a hell of i time getting my 4870x2 to run even close to its potential simply because AMD felt they had better things to do than add a profile for a 8 year old game that no one outside the flightsim community ever heard of. Same thing now, NVidia and AMD are real guick adding profiles for Battlefield or Call of Duty or Crysis2 (witch took a couple of months iirc, same with DX11 in fact, Crysis was not released in DX11 if u wanna go into that debate to), a flight sim is another matter entirely.
I could be wrong but as far as i know it took RoF until May this year before even adding Sli/Crossfire support.
Read this if you somehow think CloD is the exception:
http://simhq.com/forum/ubbthreads.ph...ml#Post3330564 (Btw not a dig of any sort towards RoF, just want to show that supported and working Sli/crossfire is not as given as many seem to think. RoF is just one example)