We've haven't had much luck with Phenom overclocking in the past, but our experiences with the 9850 Black Edition were more pleasant. I was able to get it running stable at 3GHz using some extra voltage and the same Cooler Master Hyper 212 cooler we used with the Phenom 9600 Black Edition. Rather than tell you a long tale of what I ran into during my overclocking attempts, I'll give you a look at my notes, which look like so:
2.7GHz/stock - pass
2.8GHz/stock - pass
2.9GHz/stock - no POST
2.9GHz/1.36V - pass
3.0GHz/1.36V - hang on Windows boot
3.0GHz/1.403V - BSOD on boot
3.0GHz/1.442V - BSOD on boot
3.0GHz/1.481V - pass
3.1GHz/1.481V - hang on boot
3.1GHz/1.519V - hang on boot
A "pass" means the CPU made it through 4-5 minutes of the stability test in the AMD Overdrive utility. Getting to 2.9GHz was very easy; the 9850 needed only a minor bump in voltage to make it there. Hitting the 3GHz mark took more effort and a lot more voltage. In fact, I finally settled on 1.519V at 3GHz for my testing, and even then, the system wasn't perfectly stable. I'd say this is a 2.9GHz chip for most intents and purposes. Still, I was able to take a screenshot and do some testing at 3GHz.
The CPU-Z voltage readout lies! It lies!
At 3GHz, the Phenom looks primed to take on the QX6800, at least in these two apps. I think I might have been able to extract some additional performance out of the Phenom by overclocking its north bridge (and thus its L3 cache), but sadly, our MSI K9A2 Platinum motherboard's BIOS doesn't allow for that. We may have to try it on another board soon.
I'm more than curious to find out whether my experiences here were in any way representative of what most folks will experience with the 9850. Who knows?