amskhan :
so what happens if its not unlock able?
does the whole cpu just break? or only the "extra core"
If it's not-unlockable by design (meaning that if extra cores are present, they cannot be unlocked at all) then there's nothing that you can do and the unlock will simply fail or error out. Some motherboards designed for the Phenom II X3 / Athlon II X3 can unlock the 4th core, or try to anyway. These same motherboards can also run some Bulldozer CPUs, which are not unlockable in any way.
If the cores are locked for marketing purposes (meaning that the extra cores are present and functional, but disabled in a matter that allows them to be unlocked), then the unlock may succeed.
If the cores are locked for yield purposes (meaning that part of the extra cores is faulty) then you can still attempt an unlock. The most common effect of unlocking a faulty core is that the computer will either hang during POST or crash after the operating system has enabled the other cores for handling workloads, it all depends on where the defects are and how severe they are. Sometimes the defects might not even show up until you start running Prime95, defects take all sorts of forms.