I saw a few posts here which mention about unlocking a AMD CPU 
I am totally confused as what does that mean. I have heard about overclocking a processor but Unlocking is relatively new term for me when it comes to CPU / Processors.
Can anyone clear the air for me :ashamed:
Re: What does Unlocking a CPU Mean ???
AMD Phenom II series processors are generally known for unlocking locked cores. This is how it happens :-
AMD designs Quad core Deneb and starts producing in large quantity, some of the produced cores does not meet the Quad Core standards thus AMD disable few cores and sells it as a triple and dual core as of now. But the extra core is still there inside the chip.
Now the new series of Phenom II can be unlocked easily by enabling Advance Clock Collaboration from Overclocking section in BIOS. Unlocking depends on the batch number [processor] and motherboard . Most of the boards does support unlocking and some donāt . Some batchs remains stable and performs particularly good even after unlocking as 0922apmw in X2 550 scenario, while some donāt. The batch mentioned for X2 is one the best and remains stable even after 1ghz OC.
You will not hear unlocking trend in Intel for now because most of the Core 2 Quad are 2 dual core chips slapped together in single die. While the new Nehalem architecture boast all 4cores in same die, so if in future Intel produce dual core from Quad core chip you can unlock that as well if you are lucky 
Re: What does Unlocking a CPU Mean ???
^^ Does that mean that we can actually get a quad core processor (camouflaged and sold as 2 or 3 core) in a reasonable price vis-a-vis processors being advertised and sold as Quad Core processors
Btw the explanation was really enlightening. Got to learn a new thing today
^^Yes but that restricts only to Phenom II. The newer Athlon II sports true dual core design and will not unlock to quad ..
Triple and dual core did sell a lot but AMD didnāt advertise them as Quad, things like these are generally revealed by hardware reviewing website.
^^ So now i know that when i build my HTPC what processor to take after getting sufficient inputs from experts here 
@ dark star ā¦
nice info 
Unlocking the CPU means enabling the diffused cores of a multi core CPU which do not scale up during the testās by manufacturers through bios settings (presently possible only with models of phenom 2 Series of AMD processerās only) ,
It is a matter of getting the right hardware & correct settings in bios,
also a greatly a matter of luck as all CPU are not unlockable.
Are the new phenom processors today on the market unlockable or only the old ones are unlockable??
^^ Like DarkStar Sir said all depends on luck and the processorās batch, all current generation Athlon IIx2 / IIx3 / IIx4 will remain as such, mostly the Phenom IIx2 processors unlocked to IIx4 [Deneb] OR IIx3 [Heka], but again a lot of luck as these binned cores could easily foul up and youāll not be able to proceed from the system POST screen up on boot OR they will randomly crash while running.
So yes cores can be unlocked, no this is not a fail-safe guarantee that all processors will unlock and perform.
How many tries are thereā¦ If you fail to unlock once.. Can tou try againā¦ Amd can you please give proper guide to thatā¦ Do we void warrantyā¦
You wont void warranty by trying to unlock. For unlocking you have to use mobo with SB 710 or Sb 750 with AMDās Advanced Clock Calibration. For good batches, just seting it to Auto might do the trick. For some nasty batches, you have to try individual ACC values ( ranging from +12 to -12) per core to find the most stable position.
Also unlocking is temporary, and is specific only to that boot. So just remember toe ACC values that worked. Just set that in BIOS once and its like an X4 for the rest of the life. But once you reset the BIOS for some reason, you have to fiddle with ACC again. If you put that proccy on another mobo without ACC, its just a plain X2 or X3, as the unlocking was temporary.
But the good thing is, once you find a stable unlocked proccy, it has exactly the same performance of that on a PII X4 clock to clock. On earlier days, there were certain batches called as the āCherry Batchesā which has 100% unlock success rates. That means, if you find those batch proccy on store, its like meeting a guarenteed X4 at X2ās price
some of such batches were 0922APMW, 0923CPMW, 0922CPMW etc.
Nowadays the unlock rate has been cut by 1/4 and no suh cherry batches exists or people are lazy to research and find cherry batches as the unlocking thing has gotten old.
PS: i was lucky to have one 0922apmw which i was sure was a cherry, and set ACC auto on very first boot itself. Easily does 4Ghz+ on all cores.
Very good explanation from dark star +1 from me.