Wow! Impressive! What voltage are you feeding that monster? I'm running the same chipset on a different board (with lower temps) and I can't push higher than 750mhz with a .06v increase. I could definately push the voltages harder, but I haven't tried.
At 800mhz I have the driver crash running the "Heaven" benchmark.
Increasing from my board's stock 650mhz to 750 (+.060v) gives me a 8.65% increase in FPS, and takes me from 263 to 283 points (I'm running a 640x480 dx10 AF1 AA0 benchmark)
EDIT: Whoops, I forgot AOD manages the NB Voltage as well, and my auto-settings were removed by AOD once I got into windows.
I set AOD to +.060 NB Voltage (1.168v total) and the bios to 800mhz. I finished a low res Unigine Heaven benchmark with a 11.5% increase over the 650mhz "stock" (overclocked) speed! This is great for me!
I've not confirmed this to be stable by any means, it was just stable enough to run a benchmark. I'm going to run a 3dMark06 benchmark, reclock it to 500 (stock, not overclocked) and do that again to get a total overclocking increase.
I'm running a blog at wordpress:http://chisleu.wordpress.com/2010/02/28/overclocking-in-the-world-today-has-grown-more-difficult/
I'm keeping it updated with my AMD AM3 Phenom II X4 955BE / HD 4200 / HD 5830 overclocking experiences/info/results.
I will keep adding more links to it as well. Kind of a go-to resource for me when I want to find info I forgot. haha