Okay, GTX 780 has higher performance rather than the GTX 770, right. But consider the prices. GTX 780 is around $500 up while the GTX 770 is $300-$400. If you can get make a SLI of GTX 770 with a price of $350 each (if there is), it will outstand the GTX 780. But since you are in budget mode, then go for the GTX 780.