When playing some AAA game titles like Metro Last Light or Crysis 3 in multiple-monitor configuration, the game requires over 2GB memory. the difference is obvious. I would rather buy 780 3GB or 770 4GB card for "futureproof" especially for 2nd screen support on Battlefield 4. SLI consumes too much power.
At 1080p, which the OP is using, anything over 2GB isn't necessary and the 780 is overpriced for the performance.
Hi yes. As of right now im using 1080p but come december I will br usong 3 monitors. Also next gen games are most like going to be using 3gb or mkre of vram wont they. So if id get a 4gb card now I can always sli another 4gb in the future. Or would sli 2gb sc 770s give more performance then a single 4gb card as stated by another user.