Unlock a Phenom 2 X3's fourth core

AMD have had a pretty good architecture going with their current Phenom II CPUs, based around a monolithic design that includes four cores on the one die.

Intel's Quad Cores in the Core 2 Quad have been essentially been two dual-core dies on the one package, giving a total of four cores split in the middle.

The advantage of the monolithic design is that you don't need to have the cores jump through the FSB or the HT bus to communicate, but a major disadvantage is that if a single part of the chip is faulty then there's a large possibility the entire chip will be unstable. But if only one of the four cores is damaged, why not just disable it and let the other three functional cores keep going? And that's exactly what AMD did.