In Dragon Age the HD 6970 was 37% faster than the 5870, the 7970 was 50% faster than the 6970, the 7970 GHz Edition brought an 8% boost and the R9 290X topped that by another 24% with 52fps. Raising the resolutions increased the margins for every comparison. The 6970 was now 60% faster than the 5870, the 7970 was now 81% faster than the 6970 and even the 7970 GHz Edition is 14% faster than the standard 7970. Finally the R9 290X was 39% faster than the 7970 GHz Edition.
The Crew is really only worth comparing at 2560x1600. Here the Radeon HD 6970 was 29% faster than the 5870. The 7970 was 42% faster than the 6970 and the 7970 GHz Edition was just 9% faster than the standard 7970. The R9 290X results are invalid as it was limited by the 60fps cap, but even so it was still 25% faster than the 7970 GHz Edition.