A family of AMD Phenom II processors, which were produced in 2009, has got various models with two, three and four cores. The AMD Company has produced dual- and three-core processors by disconnecting one or two cores in a four-core processor. This was explained by saving: if there is a fault in one of cores of four-core processor, it was not disposed; the fault core was turned off and processor was sold as three-core one.
As it turns out, a locked core may be turned on with the help of BIOS, and some processors which were unblocked may normally operate with all four cores. This phenomenon may be explained by the fact that there were fewer faults during production of four-core processors, and manufacturers could forcibly inactivate definitely operating cores because of the demand for dual- and three-core models.
Most models of this family were successfully unlocked: Phenom II Х3 7хх, Phenom II Х2 5хх, Athlon II ХЗ 7хх, Athlon II ХЗ 4хх and some others. There is a possibility of cache memory L3 unlocking in four-core models Phenom II Х4 8хх and Athlon II Х4 6хх, and the second core – in a single-core Sempron 140.