I was reading up on overclocking GPU's and I have a nVidia 8500GT by ASUS ans I am playing around with overclocking it. Does anyone have any experience with overclocking GPU's i was reading that at the high end one could only get +10% on both Ram and processor speed out of a card. I am able to easily and stably overclock my proc from 459mhz to 567mhz, and ram up to 472 mhz all while the card not going above 63 deg cel. Is this safe to overclock this much, or am I going to fry my card?

There's a program out there called ATITool, IIRC it has a mode that steps up the memory and GPU speeds a few mhz at a time then stresses them and tests for artifacts; once it starts detecting artifacts it will step down until it's safe... I'm pretty sure this was ATITool (Works with nvidia too)

Again, I'm not too familiar with current video card specs, but I know in the past they generally ran much hotter than CPU's and it was fine.

I used ATItool with my x1600pro a few years back and it worked great. I ran my GPU at like 90c under heavy load and never had it crashed. I never tried to OC my 8600gts because the mem clock is already crazy fast in the 2000mhz range.

I got almost 30% on my Nvidia 420. Frankly, I doubt it's worth it. To get a useful overclock, you'll need a bunch of cooling gear(I mounted a P2 heatsink on the front, and a P3 heatsink on the back), and even then, you'll be lowering the lifetime of the card.