You can overclock the RAM (to gain mhz), but generally KrazyNutz is correct, with a 6800 NU card, even when overclocked you can generally only get about 800 mhz from the RAM.
My card will allow me to overclock up to the GT speeds, but only seems to run 800 mhz and still be stable. Anything higher than 800 mhz, and my benchmark scores go down.
Basically you can overclock/mod a 6800 NU, and get near GT performance, but in the end the GT is still going to be a better card (Afterall it does cost more). For me, I couldn't justify the price, so I go the NU, to you the performance may be worth more, so the GT may be a better choice
My Desktop: <A HREF="http
/Mr5oh.tripod.com/pc.html" target="_new">http
/Mr5oh.tripod.com/pc.html</A>
Overclocking Results: <A HREF="http
/Mr5oh.tripod.com/pc2.html" target="_new">http
/Mr5oh.tripod.com/pc2.html</A>