Since AMD introduce Phenom II, which improves from it's predecessor in both power consumption and performance. the favorite bit of enthusiastists is it's ability to unlock cores. AMD had triple cores in Phenom cpus, which was originally a quad core but one core was locked. Afterwards, with the birth of 790GX + SB750, A.C.C. (Advanced Clock Calibration) was introduced. AMD claimed it can enhance OC ability, as long as using it with A.O.D. software. Although A.C.C. enhanced OC ability, Phenom is still far behind intel core 2 cpus. Later AMD introduced SB710 to replace SB750 for a reasonable price,(Actually a SB750 without Raid5 function) making AMD platforms more competitive in cost/peformance view, which is more friendly to average users. When the Phenom II X3 series came out, some user found that if you enable A.C.C. in bios, you can unlock the disabled core, Adding further strees test, you may physically make triple cores to quad cores. According to AMD, this function should be a bios bug, but it won't stop enthusiasts trying. Recently, every motherboard makers see this as a "MUST HAVE" option in their motherboards. Interestingly, some X2 cpus can also be unlock to X4 ones. With the cheap price of X2, more people are willing to try thier luck to unlock cores. If you can unlock your cpu, you are a lucky guy. If not, it's your destiny, or try another one. This is as interesting as OC. Here is a simple guide to unlock cores. PLATFORM: CPU:AMD Phenom II X3 720BE& X2 550 RAM:ADATA DDR3 1800+ 2GX2 MB:ASUS M4A785TD-V EVO(though stock 0211 bios do have unlock ability, but bios since 0218 is recommanded) VGAnboard(HD4200) HD:SEAGATE 7200.9 160G POWER:FSP ZEN 400W OS:XP X86 SP3& WIN 7 X64 RTM POST screen Press DEL to enter bios Phenom II X3 720，BIOS version 0218 enter Advanced Setting CPU Configuration，it's still Phenom II X3 720 for now nothice Advanced Clock Calibration, total 4 options Disable, Auto, All Cores, per core Choose Auto, Unleashing Mode will come up afterwards. Please Enable it, or you won't be able to unlock. Jumpfree Configuration ( Leave it as Auto) Press F10 and save BIOS Restart and enter bios, you can see cpu is Phenom II X4 20 in the main menu now. Enter OS to make sure the unlock is successful, in CPU-Z it shows quad cores correctly. Making sure cpu is stable, run Orthors to give cpu full loading. 43 minutes 1hr over 1 hour Next we test another way of unluck cpu. In Advanced Clock Calibration, choose All cores, and enable Unleashing Mode again F10 save bios and exit. In OS, CPU-Z also shows 4 cores correctly. stress test 2 minutes 48 minutes 1 hr 1.x hr WIN7 OS still shows all 4 cores correctly 13 minutes 26 minutes 2hr 45 minutes Basically we can say this X3 720 is successfully unlocked. Phenom II X2 550 unlock test CPU info Phenom II X2 550 Advanced Setting, still Phenom II X2 550 CPU Configuration Choose Auto，and enable Unleashing Mode (MUST) Jumpfree Configuration - ATUO F10 and save bios restert and enter bios, you can see X2 turns to X4 B50 in main menu CPU-Z, all 4 cores alive Of corese a stress test is needed. Result: only 2 cores are stable, it's a fail unlock. Sad!!!!! Adjust CPU voltage and HT Frequency still fail Let's try other X2 550 If we lower the HT Frequency of this CPU to 1600, we can pass Orthors. Cores sucessfully unlocked, but need to stable. stress test 17 minutes 1hr 49 minutes screen shot Final thoughts: In my experience, total 3 X2 550 and 1 X3 720, we managed to get 2 of them stable. That's 50% successful rate. Not every can run all core stable @ HT 2000, so you might add a little voltage or lower HT to get it stable. Also aftermarket cooler is recommand if core is unlocked successfully. Unlock cores is a fun game, let's all do it. Hehe!!