Once drivers mature, more or less any game, you play the differnces will look like this:
Here you see:
6970 = 42 fps
7970 = 65 fps (
thats 54% more)
here you see:
6970 = 77 fps (faster than a 580 in this game)
7970 = 123 fps (
thats 59% more).
Here:
6970 = 52 fps
7970 = 73 fps (
thats 40% more)
Here its 45% faster.
Here the 7970 is 48% faster than the 6970.
Here the 7970 is 58% faster than the 6970.
Here the 7970 is 40% faster.
Here the 7970 is 77% faster than the 6970.
Here the 7970 is 57% faster than the 6970.
Here the 7970 is 70% faster than the 6970.
Its all about how much work, has gone into the drivers.... these cards where probably rushed out with badly optimised drivers. So in some games, they dont look impressive vs the 6970, while in others (where they did more driver work) they look alot better.
Give it a few months of driver updates, and the 79xx series will look alot better compaired to the 6970 than it does now.
So already there are games where the 7970 is 40-50% faster than the 6970, at stock speeds.
And the 7970 overclocks like a mother****er, so much so that it can end up faster than a 6990 or 590.