The 1920 cayman, even if it came true. The difference would not have been as big as many people may think. I think Xbitlabs did a comparison between performance of the 6950 and 6970 when both were clocked the same and the difference was 2% literally(the difference between the 5870 and 5850 were similar when both had the same clocks). The reason barts was so fast for the size and shader amount is that the chip had basically reached the maximum return on investment in regards to shaders. Adding more shaders after this point added far less gains, which is why the difference the barts to cayman difference was not as big as it should have been. Cayman with 224 5d shaders vs the 384 4d shaders. At this point, I think the current architecture from AMD is unbalanced and has too much shader power. There are some games where the architecture shines, but even in this case it usually just matches or just slightly beats fermi. It is the reason AMD has to switch architectures, because VLIW4 and VLIW5 has run out of legs. But man what a ride and it had freakish longevity.