Phenom II 555 Overclock:

Unlocking disabled cores of Phenom II 555 X2, and overclocking it to 4GHz!

In this article I will show you advanced techniques of overclocking the Phenom II 555 family processors. This will include unlocking and stabilizing disabled cores, and also overclocking Memory controller and RAM – memory.

Hardware specs:

Default Settings:

Part: Model / Maker / Version:
CPU: Phenom II X2 555 [at] 3.2GHz
MB: Asus M5A99X EVO
BIOS: v.1208
RAM: 2x4GB DDR3 1600MHz C9 Corsair Vengeance CMZ8GX3M2A1600C9R
VIDEO: Sapphire Toxic 5850 1GB [at] 765MHz / 1.125GHz
COOLER: CoolerMaster 212 Plus
PSU: PowerColor 600W
HDD: 2x500GB Seagate 7200rpm RAID 0

Overclocked Settings:

Part: Model / Maker / Version:
CPU: Phenom II X4 B55 [at] 4GHz, NB [at] 2.8GHz
RAM: 1600MHz [at] 8-8-7-15-24-1T
VIDEO: Sapphire Toxic 5850 1GB [at] 915MHz / 1.215GHz

The PC inside:


Unlocking disabled cores

Unlocking disabled cores of Phenom II X2 (Family) has been one of the most discussed topics over the Internet. The opportunity of buying Dual-core processor, and then after some tweaks getting a four-core processor, was the dream of every enthusiast.

However, most of the official benchmark-websites, did not succeed in unlocking and stabilizing second two cores, and the enthusiasts got confused – was that merely a marketing trick and a speculation?

There is not a straight forward answer. For sure there are processors, that cannot be unlocked. But if you have one of these CPUs, why not try and get most of it?

With that question on my mind I went to one of the local PC-Stores and bought Phenom II X2 555 processor ([at] 3.2GHz). Once I got home, and assembled my PC, I tried to unlock directly the locked cores. I was a little disappointed. The processor was totally unstable – even Windows was showing blue screens during load. I headed up to Google, and searched for any information about that topic – Stabilizing Unlocked Cores of Phenom II...

After some deep searching I found some interesting articles, which claimed that most of the unsuccessful unlocks of Phenom IIs, were due to the enthusiast’s incompetence. Those articles stated that when the processor succeed to start the computer with these defective cores turned on, in most of the cases they could be stabilized after the below steps:

  • Incrementally increase Vcore (1.45v – 1.5v MAX)
  • Incrementally increase Vcpu-NB (1.2v – 1.3v MAX)
At the end, the processor was still unstable. Here I can add some additional steps for my current Asus MB, that helped me to fully stabilize my Phenom II X2 555:
  • increase CPU load Line Calibration
  • increase CPU/NB load Line Calibration
  • increase CPU Current Capability
  • increase CPU/NB Current Capability
  • increase CPU Power Phase Control

Fully stable Phenom II X4 B55 processor

After spending some days in tweaking my motherboard settings, finally I got my CPU stable, with these settings (note that most of them can be lowered for daily use):
Setting: Voltage:
Vcore: 1.45v
Vcpu-NB: 1.275v
NB: 1.15v
HT: 1.25v
CPU VDDA: 2.525v
DRAM: 1.6v
Setting: Value:
CPU load Line Calibration: Extreme
CPU/NB load Line Calibration: Extreme
CPU Current Capability: 130%
CPU/NB Current Capability: 130%
CPU Power Phase Control: Extreme


The next step of course, was to find out how much the Phenom II X4 B55 (The processor got that name after unlocking the additional cores), the RAM memory and the CPU/NB can be overclocked with these settings.

I will say that I have been pleasantly surprised, when the processor Phenom II X4 B55 with ease gets to 4GHz stable clock, with CPU/NB [at] 2800MHz. The RAM was not-so overclock-able – and end up with timings: 8-8-7-15 [at] 1600MHz. Sapphire Toxic gets to theamazing 915MHz / 1215MHz overclock after BIOS update.


In next section you can find benchmarks before and after the unlocking and overclocking, and also see what the benefits are:
Before Overclock: After Overclock:
WindowsRating before overclock WindowsRating after overclock
AsusAllStats before overclock AsusAllStats after overclock
CPUZ_Stats before overclock CPUZ_Stats after overclock
Sandra_MemoryBandwith before overclock Sandra_MemoryBandwith after overclock
Sandra_CacheAndMemory before overclock Sandra_CacheAndMemory after overclock
Sandra_MemoryLatency before overclock Sandra_MemoryLatency after overclock
Sandra_ProcessorArithmetic before overclock Sandra_ProcessorArithmetic after overclock
Sandra_GPBandwidth before overclock Sandra_GPBandwidth after overclock
Sandra_GPProcessing before overclock Sandra_GPProcessing after overclock
Cinebench_11.5 before overclock Cinebench_11.5 after overclock
3DMARK_VANTAGE before overclock 3DMARK_VANTAGE after overclock

Stability tests

Please note that after unlocking the additional cores, the processor thermal sensor is not accurate! For example with CoolerMaster Hyper 212 Plus, if my Phenom II X4 B55 gets above 53 degrees by Celsius, it gets unstable. So keep your processor cool!
Description: Screen Shot:
3DMARK Vantage Settings: 3DMARK_Settings
Windows7 Rating Inside: WindowsRating Inside
Prime95 Blend Test: Prime95Blend
Prime95 InPlace Large FFT: Prime95 InPlace LargeFFT
Prime95 Small FFT: Prime95 SmallFFT
SuperPI 8MB: SuperPI_8MB


From my point of view, the risk is worth with Phenom II X2 555. I never listen to the advices not to count on the core-unlock feature. And thus I am winning twice the performance for the same price. But your case may not be the same. Look at the numbers below and decide fast, because Phenom II family is quickly disappearing from the vendors.

Performace Increase

Vladimir Iliev 2012© All rights resered.