WHAT is SLI?



Double the performance? Hell no, youre looking at 1.5 x 1 gpu. Just so you know, 1 more powerful gpu is always better than 2 less powerful ones.
 
when your running 2 290x there is no single card that will and pushing a resolution like 5760x1080 even those cards are barley enough and as you can see i said that they dont actually double and 1.5 less accurate in my experience ( 2 780 classifieds 2 270x 2 280x and 2 290x) it has always been more than a 50% increase