I have two 670s in sli, but cant understand why when I use the txaa as a antiliasing all I get is bad performance as if I were using a single card. All I notice is this: when I use a different antialiasing the two cards can get to 100% GPU usage when I use the txaa, can't get past 60%. The sli works well and it's not bottlenecked, since in all game fps doubled ( at least when I use fxaa, msaa or smaa). I have a fx8320 overclocked at 4.3Ghz, 8 gigs of ram (cl10-10-10-24) overclocked at 1866, corsair cx750m supply the entire build the power and a 990fx sabertooth by Asus. I was wondering... why this weird behaviour?