does better cooling result in higher overclocking?

Just want to know if better cooling results in a higher stable clock when overclocking a video card or does it just make for a safer overclock. I have a x800 gto2 that won't go past 500 core clock using ati tool and was wondering if its because of using the stock cooling. It gets up to about 70C which is hot, but I don't think dangerously hot.

 

its not dangerously hot, no, but i would definantly consider a better cooling solution if i were you.
the stock coolers on the gto2's are pretty good (at least from what i can gather, as i dont actually have one...). but a better cooling solution *can* quite possibly get you a higher overclock, but most importantly i would greatly help increase the lifespan of your card.