it could be that your CPU just is a dual core model.
it could be that the core unlocker is under the overclocking options for the board, it is for my asrock board.
That could definitely be the case, which I'd be fine with.. if I had a way of finding out one way or another.
I didn't notice a section under BIOS for OC'ing though. Would that be under Advanced options, as well? And if so, I'm still not seeing it