i can say from experience that the GTX 780 will run with no problem i have the stock 780 and since you want the ACX version it may run a little better.I also agree with 'subhadeep082012' a 770 4gb is useless if you dont have multiple monitors 3gb of VRAM is enough... but in sli 2 770 would have better performance but you could get more hiccups since you will be using 2 cards instead of one.