to give you an idea, BF4 uses almost 2GB at 1080p, ultra 4xMSAA, but GTAIV tells you how much it need with each graphics settings and it seems to go above 2GB with all max'd out. I think 3GB is the sweet spot currently, so I got 2x 7950 when they were cheap. BF4 on 3 monitors uses 2.75GB.