Earlier this year, a Korean source had pointed out an easy method to enable a fourth core on the Phenom II X3. This was made possible by the way AMD has been designing its triple-core and dual-core processors based on the K10 "Stars" architecture: by disabling one or two cores on the quad-core die. "Sloppy" BIOS coding lead to the Phenom II X3 anomaly. It looks like a somewhat similar mod enables not one, but two cores on the sub-$100 Athlon X2 7750 Black Edition. A Korean technology website GiggleHD.com has reported a successful unlock of two cores.
The method is similar to that of the Phenom II X3 unlock: using flaws in BIOS code to enable cores, by enabling the "Advanced Clock Calibration" feature in the BIOS setup. The OS, Windows XP SP3, was able to see the processor as a "AMD Phenom(tm) FX-7750", while CPU-Z reads the name string correctly and lists the core count as 4. We are trying to gather more information about this, especially about the name string, and will keep you updated. Details on the rest of the system (the motherboard) is not provided, though you can conclude it is based on an AMD chipset with SB750 southbridge, since that's the only qualified platform with ACC support.
Source : Techpowerup!