I'd like to second the suggestion of a hd7970. Not a ghz edition card, though. One with a decent heatsink fan(maybe with 2 fans?). Should be cheaper than a gtx670 but run just as fast. Should overclock well past ghz ed. speeds too, making it faster than a gtx680. I got the impression the extra voltage a ghz edition affords can limit a card's overclocking. better to tweak volts and clocks yourself for the best results. Don't forget to raise the power tune limit in the catalyst driver or your overclock will throttle when you max out the tdp.