When it Will start playing games with Low framerate ill Just add one more 760 hawk or is it better to get single r9 280x vapor-x? Answer theese 2 questions
When frame rated begin to drop some distant date in the future, look which graphics cards will be available then for which prices, and then make your decision. The right card may well be one that is not yet on the market today.
A Core i5-4670 with a Radeon 7770, 16 GB DDR3-1600 RAM on an Asrock B85M mainboard and Xigmatek cooler. I also own a Soundblaster XFi Titanium PCI-E sound card.