I just upgraded and got a 5930 process for $500 at a local Micro center.
760 Watt PSU, 5930k, 16gb 20133 ram, Samsung 850 pro ssd
I bought the 1st 670 4GB about 2 years ago for $430 so, buying a 2nd for $130 seems like a good deal.
I see this benchmark on BF3 but wonder what BF4 would do...