AMD has achieved its goal: the HD 7970 GHz Edition is the fastest single-GPU graphics card in the world. Thanks to the 125 MHz higher GPU clock, than that of the regular HD 7970, the card beats NVIDIA's GeForce GTX 680 by about 2% averaged over all our benchmarks and resolutions. At 2560x1600 the increase is even larger with 8%, but that's not because HD 7970 GHz is so strong at that resolution, but because NVIDIA is weak. Compared to the non-GHz Edition HD 7970, the card tested today is around 10% faster on average, a sizeable improvement.
Unfortunately this performance increase comes at the cost of increased power draw. It seems that AMD has picked the highest clocking chips and gave them some extra voltage to ensure things are stable. As a result we see significantly higher power draw when gaming. Performance per Watt is also much worse, even with the 10% performance increase taken into account. The jump in power consumption also directly affects temperature and noise. While temperatures are just ok with 83°C under load, noise is completely unacceptable. The card runs at 51 dBA - one of the noisiest cards ever tested, noisier than NVIDIA's GeForce GTX 480.
AMD has introduced a new "boost" clocking mechanism with this card, but it is nothing close to what NVIDIA offers. I think a more accurate description would be that the card "boosts" from its default of 1050 MHz down to a clock speed of 1000 MHz and reduced voltage, when it senses a power overload situation, that's it.
AMD's HD 7970 GHz edition is priced at $499, the same as NVIDIA's GTX 680. While this might seem enticing at first glance, since the GHz Edition is faster, NVIDIA's card wins at power-draw, noise, and manual overclocking, with the better card overall. I find $499 is just too high to really draw away much attention from the GTX 680, if the HD 7970 GHz Edition was $450 I'd definitely consider it, until that happens I'll happily take a GTX 680, or even GTX 670, which offers better price/performance at not much lower performance.