I have a new build coming up
but I currently have evga 570's in my case
think I will have to go with 670's
That is one option, but check out the benchmarks... Here's one from Anandtech
, though most of the reviews I've looked at show very similar results... the 660 is a significant upgrade to the 570 even at 2560x1600 & performs within a couple percent of the 670 in most games for $100 less... Battlefield 3 @ 2560x1600 Ultra Quality FXAA high from avg 53.9fps for eVGA Superclocked 660 Ti, to avg 58.4fps for Gigabyte's top card, while the 570 (not sure which one) gets just 39.7fps on average... Check out the Overclocked Gaming Performance page
where the Gigabyte 660 Ti even beats the 670 they used in a couple games...