690 = 1000
What is the best way to spend your money?
2x7970 thats what
Eh, dunno about that last part lol. With either a 3x670 or 2x7970 set-up, you're still going to be producing a boatload of heat and using more power than the single 690. If you are not concerned about price, I would actually just buy 1 gtx 690 and even sell off your 670 for some extra cash.