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Unlocking 4th core on AMD Phenom II x3 720 BE

  • AMD
  • Core
  • Phenom
  • Overclocking
Last response: in Overclocking
January 3, 2012 1:19:49 PM

Hi Everyone,

I'm posting my question to the overclocking forum thinking that the right people are probably here, even though my question is around unlocking a 4th core.

I recently picked up a AMD Phenom II x3 720 BE and thought I might experiment around with unlocking the 4th core - even though I know it's really a hit/miss chance if my processor is capable.

I have a Gigabyte motherboard (with latest firmware) and in setting ACC to "Hybrid" and the other selection (forgot the specification) I tried both "All cores" and "per core".

Each time the PC posts fine and I show the proc as "Phenom II x4 20" in BIOS - which is what I expect. However, whenever it boots into Windows 7 (32 bit still), it blue screens.

Now I understand this might be my "sign" that my 4th core cannot be enabled - but getting up to this point, has anyone tried any tricks (with the core % values or voltage) that might be a recommended option?

I did some Google searching and I couldn't necessarily find any recommendations on if a % change per core could make a difference -and I didn't want to poke around and potentially break the processor in the process.

I know it's also a stretch - but should I even make the processor changes and boot into a clean, newly installed version of the OS to see if that makes a difference? I wouldn't think so, but I'm open to ideas.

BTW, once I put the ACC setting back to "auto" the PC boots into the OS fine - so it's definitely some BIOS setting or the unlock itself causing this problem.

Any tips, suggestions, etc, are greatly appreciated. I fully know this isn't a guarantee I'll get the 4th core to work, but it's definitely fun to try......


BTW -I also upgraded the fan/heatsink combo (no longer using stock), just in case the 4th core or extra voltage will cause more heat.

More about : unlocking 4th core amd phenom 720

a b K Overclocking
January 3, 2012 6:25:06 PM

Faulty fourth core
Related resources
January 9, 2012 3:34:39 AM

Umm ACC stands for advanced core control and what that is, is a feature added in with the phenom 2 series which allows the motherboard to adjust voltages core dependant instead of being manual which used to be the case when overclocking and having a core fail. the feature you are looking for is UCC which is hit and miss but i have succesfully unlocked a phenom 2 x4 960 to a hexacore on a ASRock 870 extreme 3 mobo
February 15, 2014 12:05:07 AM

you can try voltage bump but chances that the unlock will stabilise are odd.