A while ago there were reports about unlocking the fourth core of some Phenom II X3 processors, and now ASRock informs us that this trick can also be done on some AMD Athlon II 400 and 405 processors. The motherboard maker says users can activate the fourth core of some of these processors simply by activating the AOD-ACC option in the BIOS:
The AMD Athlon CPU we tested this time is AMD Athlon II 400/405, which is scheduled to be announced soon around this summer. The
CPU-Z below shows that we could upgrade AMD Athlon II 400/405, the X3 cores CPU into X4 cores simply by enabling the AOD-ACC
function. However, not every AMD Athlon II 400/405 CPUs can be upgraded. We tested some CPU that some succeeded but some failed
with a certain percentage.
This trick works on the following ASRock motherboards: