Overclocking
Because it's a Black Edition, overclocking the Phenom II X3 720 is just a matter of turning up the CPU multiplier in the BIOS. For my run at glory with the 720, I used the Asus Socket AM3 board, just for fun, along with a ridiculously huge Cooler Master heatsink/fan combo. I tested stability by booting into Windows and running a multithreaded Prime95 stress test. The log of my attempts is below; the process was fairly simple, and I started at 3.4GHz based on my prior experience with Phenom IIs.

-3.4GHz, 1.325V - BSOD on boot
-3.4GHz, 1.35V - Boots Windows, reboot in P95
-3.4GHz, 1.375V - BSOD in P95
-3.4GHz, 1.4V - Seems OK
-3.5GHz, 1.425V - Boots Windows, reboot in P95
-3.5GHz, 1.45V - Seems OK
-3.6GHz, 1.45V - Reboot in P95
-3.6GHz, 1.475V - BSOD in P95
-3.6GHz, 1.5V - BSOD in P95

With a relatively modest number of attempts, I'd determined that this X3 720 can run at 3.5GHz, at 1.45V, without much trouble. Not too shabby.

Overclocking the Phenom II X4 810 was a more complicated process since I had to turn up the base HyperTransport clock in order to raise the CPU speed. Making this work involved more voltage tweaks, reductions of the HyperTransport multiplier, adjustments to memory clocks, and several forms of psychotropic drugs. Eventually, I settled on the following stable configuration: a 3.458GHz core clock at 1.45V, with a 266MHz base clock, a 1596MHz HyperTransport link, and 1418MHz memory. I'd given additional juice to the north bridge and RAM, along with a slight increase in HyperTransport voltage, when all was said and done. Again, not bad, but getting there was a bit more work than with the X3 720, and I was less confident in the overall stability of the system at the end of the process.

What about performance?

At 3.5GHz, the X3 720 is really stinkin' fast. The X4 810 is less impressive at 3.46GHz, probably held back here by its smaller L3 cache and slower HT/L3 "uncore" frequency.