Quote Originally Posted by Jackel View Post
Performance scaling will almost certainly be dependent on the resolution you're running at as well. I run a single 680 (2gb launch) and average 60-85 in all the areas where I need performance to matter. This is stable at 1920x1080. Adding a secondary 780Ti would see minimal gains at this resolution even on max settings but if you're running a higher resolution you'll almost certainly benefit from the extra power and added Vram.
Unfortunately, the VRAM for both cards isn't pooled like when extra RAM is added to mobo, the VRAM in an SLI configuration works in parallel. So the assets to be rendered are sent to the respective card, which then only utilizes the VRAM available on board to store data. The GPUs cannot access data stored in VRAM on a different physical card. It's a damn shame. The benefit is that less VRAM it utilized, which means more room in VRAM to store computational data for graphical effects like supersampling, ambient occlusion, tessellation and more buffered frames.