Unlocking Phenom II X2 and X3 Cores

What you'll need:

• Motherboard with SB710 Chipset or higher
• Phenom II X3 720 BE, Phenom II x2 550 BE
• Bios with ACC (Advanced Clock Calibration) feature
• Luck

In my case, I used Asus M4785TD-M EVO to unlock the 4th core of my lucky Phenom II X3. The unlocking process is very simple.

At startup, you have to go to BIOS by pressing "Delete" in my case or F12 on other motherboard. Then go to:

• Advanced Tab
• Selec CPU Configuration
• Set ACC to Auto
• Enable Unleashing Mode
• Set Active CPU Cores to 4 cores operation
• Save and Exit

 If your computer doesn't boot properly or reverted to its default bios settings then the 4th core is not yours. It may be defective or your processor doesn't belong to the lucky batch (you can check the lucky batch in the link below). If the computer boots up with no problem then you're almost good with your unlocked 4th core. A good way to check if the 4th core is unlocked is by running CPUZ or checking it in the task manager.

Unlocked:

Checkout the Code name, its Deneb. It's also the code name for some AMD Quad cores.

After unlocking the core, you may want to check the stability of your system by stress testing using Prime95, OCCT. Some Phenom II x3/x2 processors can be unlocked but not stable at all. Stress testing it for a minute will result a BSOD, hang, sudden shut off, etc. It's very important to check the stability of your system first to avoid any unwanted results.

Here are the detailed list of Phenom II series that can be unlocked:
http://www.overclock.net/amd-cpus/535501-amd-phenom-ii-core-unlocking-guide.html