BIOS exploit enables additional AMD CPU cores

By on April 25, 2009, 6:38 PM
It was noted by a Korean source earlier this year that an easy method to enable a fourth core on the Phenom II X3 had been found. How easy, you wonder? Simply by setting the Advanced Clock Calibration (ACC) feature found in the BIOS of various motherboards to “Auto”, the system is able to utilize the otherwise disabled core.

The exploit is possible due to the way AMD has been designing its dual and triple-core processors based on the K10 architecture, disabling one or two cores on the quad-core die. Careless BIOS coding lead to the Phenom II X3 discovery and it would now appear that enabling the ACC feature unlocks not just one, but two cores on the Athlon X2 7750 Black Edition.

While it is entirely reasonable to consider that AMD may have opted to disable cores on inferior quad core chips otherwise unfit for sale, any stability issues can easily be remedied by reverting to the default BIOS configuration. If you fit the criteria and belong to the adventurous type, give it a shot and let us know how it goes in the comments.




User Comments: 6

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camuss15 said:
Isn't this old news anyway? I've read about people doing this to several AMD processors on Newegg reviews.
tengeta said:
Weren't some of those also quad cores with a bad core? It might not be a good idea to activate them if thats the case.
[-Steve-] said:
I often find it frustrating reading comments at times.camuss15 I am not sure if this is in fact old news “anyway”. While it could be, I have only heard of users enabling the fourth core on Phenom X3 processors not the third and fourth cores of the Athlon X2 processors.tengeta did you fail to read the last paragraph? Pretty much covers exactly what you just said in plain English…
Jibberish18 said:
I've only heard of people doing this on the Phenom II's (Probably because I stopped caring about the original Phenom's) and I also haven't heard of it working on the Kuma's (Is that the processor we're talking about here?) I'm confused though, would they actually use a Defective Quad Core as a solution for a Dual Core? I thought they only used defective Quad Cores for their X3 line of processors?
scud1337 said:
They mainly use defective Quad Cores for their X3 and X2 Phenom line,but if there was some shortage on defective ones they can allways use agood Quad and disable 1 or 2 cores to get the other one.
captain828 said:
[b]Originally posted by Jibberish18:[/b][quote]I've only heard of people doing this on the Phenom II's (Probably because I stopped caring about the original Phenom's) and I also haven't heard of it working on the Kuma's (Is that the processor we're talking about here?) I'm confused though, would they actually use a Defective Quad Core as a solution for a Dual Core? I thought they only used defective Quad Cores for their X3 line of processors?[/quote]It's easier to use the same wafers and design for all your CPUs than to have a different design for a dual-core, tri-core and quad-core.Given their financial position I guess it's understandable.This is what the GPU industry has been doing for a long time. It's just that they usually laser cut the core or ROP they want to disable, so there's no way of "hacking" back the missing feature.No idea why AMD didn't laser cut the bad core(s).
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