I also have a 8800GT. It isnt overclocking very well, atleast not the way people said it would.

The core maxes out @ about 734mhz, memory 1080 and the shader *drumroll* 1674....

Maybe the its the heat thats crippling the overlock, with the fan @ 60% i get about ~75c loaded with these clocks. Im waiting for the hr03 gt version and then we'll se if I can push it further.
I was thinking that nividia intentionally lowered the vcore/vmem on these cards so the woulnd't beat both GTX and ULTRA. I mean, you can see there's alot of potential but it feels like the clocks are held back by low voltage.