just today i have installed a new monitor and have noticed a considerable drop in performance in crysis the montior is bigger 22" from a 17" but i have not increased the resolution before, without sli enabled i used to get on 23-27 fps 1280x1024 very high and get exactly the same on my new monitor but with sli used to get 34-45 fps and now i get the same as if i were not using sli whats going on i have it enabled in ntune and think its working with other games (nothing really pushes the system hard enough though appart from crysis) i have the last drivers installed which i got last night and have not played crysis for a while until today could the driver be doing this?
If ALL settings are the same, resolution, driver version, etc... then it makes no sense that your performance would change AT ALL.
However, SLI really doesn't kick in until you reach resolutions higher than 1280x1024 in many cases. I'd suggest you try playing with different resolutions and see what happens.
Depending on your machine, you could be CPU limited too. (You haven't mentioned CPU or Video card models, which is important in a tech situation like yours).
At higher resolutions, SLI can kick in and isn't as limited by the CPU. At low resolutions, CPU is more important and SLI really can't do much of anything.
Since you've got a 22" now, try using the 1680x1050 Resolution if yours uses that as its native (max) resolution. See what happens.