I easily maxed out my xFx 5750 clocks to the full limit the ati control panel would allow. Core @870mhz and 1GB DDR5 ram @1430mhz (5720 Mhz DDR5).
I have yet to try another utility to raise the clocks higher. The 5750 with typical oc provides more than enough performance for the games I play. I like better that it accelerates Adobe Flash and some regular video playback as well. I can encode video's maxing out all 4 cores of my Q9450 cpu, program in vb.net, and watch high def all at the same time with no hicups in the least. So my demands are different than most people who may want absolute gaming performance. But for those who don't demand the max possible performance just might be happy with the 5750, and thus the performance of the new nVideo card that competes with it. I guess power consumption, features, and price will determine which card is bought.
Jason