The 6600GT GPU isnt fast enough to utilize the 256MB of ram and sometimes gets slowed down, that's why the 128MB is better.'
It's not only like the GPU and the core clock speeds, and the mem bit. :up:
Don't forget teh pipelines
That's why the 6600GT is clocked at 500/500*1000* but the 7800GT is onyl clocked at 445/510 but it has 20 pipelines compared to 8, and an extra 128MB that it can actually use! So it outperformsn it by 1083084304 million miles