The 9800GTX+ ( yes I am still running one ) is about as maxed out as G92 could go. 738 core/ 1836 shaders / 2200 memory / 33c at idle right now.
I cant really get much in the way of an overclock out of mine....I think the superclocked versions are about as good as they get.
The 55nm die shrink does allow it to run real cool though especially compared to my old 8800GTS.
CPU has nothing to do with how fast the graphics card runs.