What software is best for looking at the details of a 8800 GTS 320

I have a EVGA 8800 GTS 320 MB graphics card.

When I overclock my E6750 from 2.66 to 3.2 GHz, the system is stable under load, but when I run graphic benchmarks, my graphic performance is cut in half (3DMark, in game FPS measurements). My GPU is at stock settings

So I want a software progam that would tell be the internal settings and parameters of my graphics card so I can try to invetsigate the problem.

Any suggestions?

You could also try Everest, it gives you a bit more on the rest of your system.
www.lavalys.com

GPU-Z!