Summary: First, this card is very well designed, quiet and cool. I used it to replace dual 6950's in crossfire because I didn't want to deal with all the driver related issues SLI/Crossfire have. I'm very pleased with the default performance, but a bit disappointed that you cannot overclock this card.
Summary: After reading about how well these Ghz versions of the 7970 overclock, I took the plunge. I spent hour, trying everything from simple .cfg changes in Aftreburner, to registry edits, until I eventually discovered that Gigabyte have totally locked down any voltage changes. Without the option to increase the voltage, overclocking is out of the question. Even 5Hz increases without additional voltage result in blue screens.