i currently have a gtx 680 2gb and i want to start 3 monitor gaming with three 24inch 1080p monitors with like 40+fps. i was debating over if i should sell my 680 to get a 780ti. but would that be enough to play games like bf4 on max settings, with three monitors? i was also considering to get another 680 2gb to SLI but i know vram doesn't stack, but would 2gb be enough. what should i do.