Do you need ACC to unlock cores in any sercomstances?

SB = South bridge. Its a chip on the motherboard. All AMD SBs from the 750 up have ACC. This is what unlocks cores. So yes. You need ACC, which is found on the 750 and newer SBs.
 
Thee older SB710 will unlock as well as some Nvidia boards, I think Nvidia calls it nvcc (or just plain old "core unlocker") and ASRock calls it ucc.
 
A while ago I asked somethin' similar, but these guys said that there were a few other things that unlock cores. I have a AMD Athlon II X3 440 @ 3.3ghz. =D
 
I have only bought the CPU not the GTX 460. Ima savin' up. I just wanted to tweak the CPU as much as I could to get the best bang for my buck.

P.S. I like your "Four out of five dentist recomend my answers!"