It was noted by a Korean source earlier this year that an easy method to enable a fourth core on the Phenom II X3 had been found. How easy, you wonder? Simply by setting the Advanced Clock Calibration (ACC) feature found in the BIOS of various motherboards to “Auto”, the system is able to utilize the otherwise disabled core.
The exploit is possible due to the way AMD has been designing its dual and triple-core processors based on the K10 architecture, disabling one or two cores on the quad-core die. Careless BIOS coding lead to the Phenom II X3 discovery and it would now appear that enabling the ACC feature unlocks not just one, but two cores on the Athlon X2 7750 Black Edition.
While it is entirely reasonable to consider that AMD may have opted to disable cores on inferior quad core chips otherwise unfit for sale, any stability issues can easily be remedied by reverting to the default BIOS configuration. If you fit the criteria and belong to the adventurous type, give it a shot and let us know how it goes in the comments.