thx lightman for the infos!
you dont happen to have a 4890 or 4870 or better yet 4870x2 so you can do exactly the same thing on that card in the same rig?

i threw the numbers in a graph:
Pixel shader, multi fillrate, perlin noise, vertex shader simple are not bandwidth limited... yes some of these increase slightly, but the boost they get from increasing the memory clocks and hence bandwidth by almost 50% can be ignored...

complex vertex shader, shader particles and fillrate single are clearly bandwidth limited... but the gains are linear and proportional, so the gpu is definately not bandwidth crippled or starved like some people suggested... i dont think that memory bandwidth is limiting the 5870... i think its internal bandwidth or some internal architecture bottleneck...