Yeah, I read about this, but the core was turned off for a reason. Surely, enabling it, even if it works, its not going to be a fully working core?
Like I said, there have been mixed results. Looking through some threads on another forums, it's about 50/50. For some, the fourth core wasn't stable (failed P95 etc), for others, it was perfectly functional, and didn't even hamper OCs.
So you take a chance, but it's a great payoff if you're lucky