The GHz Edition lives up to its name, delivering a core clock speed of 1GHz, with its 3GB of GDDR5 memory running at 1.5 GHz. Those are stunning numbers, but the GHz Edition's real tricks are more clever than that. A new PowerTune Boost feature allows the card to juice itself with extra electricity (when there's spare juice in the system), delivering performance boosts on demand. This should translate not only into smoother framerates under pressure, but allow the card to crush GPU-accelerated non-gaming software.
In Tom's Hardware's super-thorough benchmarking, the GHz mostly lives up to expectations, either tying or beating Nvidia's comparable GTX 680 in games like Skyrim and Battlefield 3 — the only thing consistently upping the GHz is Nvidia's GTXX 690, which costs a thousand dollars.
The HD 7970 GHz Edition, by comparison, will only run about $US500 — a little more with aftermarket cooling — making it somewhat reasonable for determined games with disposable income. Look for it on internet shelves "as early as next week" from companies like ASUS, Gigabyte, HIS, MSI, Sapphire, TUL and XFX.