Man i got myself an amd athlon II x3 445 and managed to unlock the fourth core and made it a phenom II x4 b45 but unfortunately i didn't managed to unlock the l3 cache bcz there wasn't any:|...
Anyway i'm still using the stock cooler so it's safe to do it bcz my temp readings on Core Temp doesn't jump over 55 degrees C at full load for 4 hours...and it seems stable.
So about unlocking....get in bios and search for an option called ACC(Advanced Clock Calibration) and there you have it.
About the voltage, i didn't increased it when i unlocked it but i did when i overclocked it.
Right now i got the unlocked cpu running at 3.8 ghz with stock cooler and not going over 55 degrees so i'm happy