Unlocking Athlon II / Phenom II cores and L3 cache
AMD K10 family includes 12 desktop Sempron, Athlon II and Phenom II families, which differ from each other by the number of cores - from 1 to 6, the size of L2 cache - 512 KB or 1 MB per core, and the size of L3 cache - from 4 to 6 MB L3 cache or no cache at all. It's interesting that this variety of microprocessor families with different features is derived from just four base cores:
All other K10 cores are created from 4 base cores by disabling one or more CPU features. For example, Athlon II family is based on Regor, however it has one CPU core disabled. The table below summarizes what features are disabled for which family:
Identifying underlying base core is easy from the markings on the CPU. The first (line) line of markings contains family name. The second line has OEM part number. The third line, highlighted on the picture below, contains stepping code:
One of the most important parts of this line are two letters in the middle. These letters are used to determine base core:
As an example, the pictured Sempron on the picture above has "AE" letters, i.e. it is based on the Regor core, and, as such, has one CPU core disabled. The pictured Athlon II X3 has "AD" letters, which means that the base core is Propus.
There are two major reasons why certain features are disabled on AMD processors. Cache memory and extra cores on these microprocessors could be disabled due to internal core or memory defects, or to meet market demand. Unfortunately, it's not possible to tell whether the features were locked down because the core or cache memory didn't pass quality assurance tests, or because high-profile OEM company needed a large number of cheap parts with fewer cores and/or smaller size of cache. The good news is that often it is possible to unlock the disabled features. To do this go into BIOS, and look for "Advanced Clock Calibration" feature. It's very likely that you will find it in Advanced tab on the "CPU Configuration" screen. Set this feature to "auto" and reboot the computer. If the computer hangs and doesn't want to post then clear CMOS memory. If it still doesn't work you may try to increase the core and NorthBridge voltage a little bit. Be careful with voltage increases - running the CPU outside of specifications will void your warranty. Once you have the core and/or memory unlocked, run memory and CPU intensive test to confirm that the CPU indeed doesn't have any noticeable defects. We've heard a rumors that unlocking CPU features may kill the CPU and/or motherboard, but we've never seen a proof of it. So far we tried to unlock from 20 to 30 processors from different Sempron, Athlon II and Phenom II families, and in the worst case we had to reboot the system. In our experiments we've seen more than 50% success rate. Your mileage may vary.
Below is a list of different models that can be unlocked, and how BIOS identifies them:
And, finally, CPU-Z screenshots of some unlocked processors:
Unlocked Athlon II X3 400e:
Unlocked Athlon II X3 405e:
Unlocked Phenom II X2 550 (C3 core revision):
Unlocked Phenom II X2 555 Black Edition (C3 core revision):
Unlocked Phenom II X3 740 Black Edition:
Unlocked Phenom II X4 820 (not Black Edition):
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