How is it that an older model such as the 5970 can mine at higher rates than a newer 7970?
Has it had special work/production done over the time it was released? If so, I hope the same will happen with/for my card.
So the architecture and production process for the cores in the later models has changed. Usually they do this to improve game performance and don't pay any mind to bitcoin mining. It just happens that the older 5000 series cards had architecture and driver sets which seem optimal for mining bitcoins.