thats the video card i am about to get, the double vram is some incredible futureproofing. I only expect it to run games on a single 2560x1440 monitor + 2 1080p aux monitors for non-demanding tasks
watch dogs on 3 monitors 1440p? dream on. general consensus says that watch dogs is the most demanding game (with respect to vram) out yet. I would guess the 780 6GB would not even run 60 FPS on 2 of those at max settings.
To run 3 2560x1440 monitors displaying the latest games you are looking at a R9 295x2, or a SLI setup of a 780ti or above