It does not really use much at all, Windows uses 100 meg per a screen I run 4 screens atm with 10 wow's open and it does fine the 670 is a great card and basically just as fast as the 680 but underclocked a tiny bit due too nvidia did not want to just give there cards away at a lower price

This is how I have my setup with 4 screens

http://sphotos-e.ak.fbcdn.net/hphoto...94243750_n.jpg

About to get a whole new rig for $4000 Cant wait!