Unlocked? What?
Please explain :(
Processors are basically grown. I'm sure wikipedia could tell you more about the process. Anyway, they are made in large batches.
All of the processors for this particular line (talking about this AMD line) are designed with 4 cores. Now...when you make a batch of CPU's there are bound to be some defective ones. Much of the time, only one or two cores are defective on a particular CPU. Multiple CPUs in each batch will fail the initial QA testing.
If AMD chose to just throw away those faulty processors they would be losing valuable profit and would pass the additional cost onto the consumer. Instead, they choose to use those defective chips to fill in a lower market segment that doesn't need/want 4 cores, but needs or prefers the lower price.
Many times, all of the cores will work on a defective chip, but one will under perform or be unstable. They disable this core by locking, essentially changing how the rest of the computer perceives the chip. The core is still physically there, just locked. The other 3 cores are perfectly fine and can be offered cheaper.