Editing Overclocking (section)

== CPU multiplier locking ==
{{unreferenced section|date=December 2020}}
'''CPU multiplier locking''' is the process of permanently setting a [[Central processing unit|CPU]]'s [[clock multiplier]]. [[AMD]] CPUs are unlocked in early editions of a model and locked in later editions, but nearly all [[Intel]] CPUs are locked and recent{{when|date=December 2020}} models are very resistant to unlocking to prevent overclocking by users. AMD ships unlocked CPUs with their [[Opteron]], [[AMD FX|FX]], All [[Ryzen]] desktop chips (except 3D variants) and Black Series line-up, while Intel uses the [[wikt:moniker|moniker]]s of "Extreme Edition" and "K-Series." Intel usually has one or two Extreme Edition CPUs on the market as well as X series and K series CPUs analogous to AMD's Black Edition. AMD has the majority of their desktop range in a Black Edition.

Users usually unlock CPUs to allow overclocking, but sometimes to allow for [[underclocking]] in order to maintain the [[front side bus]] speed (on older CPUs) compatibility with certain motherboards. Unlocking generally invalidates the manufacturer's warranty, and mistakes can cripple or destroy a CPU. Locking a chip's clock multiplier does not necessarily prevent users from overclocking, as the speed of the front-side bus or PCI multiplier (on newer CPUs) may still be changed to provide a performance increase. AMD [[Athlon]] and [[Athlon XP]] CPUs are generally unlocked by connecting bridges ([[jumper (computing)|jumper]]-like points) on the top of the CPU with [[electrical conduction|conductive]] paint or [[Graphite|pencil lead]]. Other CPU models may require different procedures.

Increasing front-side bus or northbridge/PCI clocks can overclock locked CPUs, but this throws many system frequencies out of sync, since the RAM and PCI frequencies are modified as well.

Contrary to popular belief, the "pin mod" method which claims to unlock older AMD Athlon XP CPUs does not work. All other unlocked processors from LGA1151 and v2 (including 7th, 8th, and 9th generation) and BGA1440 allow for BCLK overclocking (as long as the OEM allows it), while all other locked processors from 7th, 8th, and 9th gen were not able to go past 102.7&nbsp;MHz. 10th gen however, could reach 103&nbsp;MHz <ref>{{Cite web|url=https://www.techpowerup.com/review/intel-core-i5-10400f/|title=Intel Core i5-10400F Review – Six Cores with HT for Under $200|website=TechPowerUp|date=May 28, 2020 |access-date=2021-12-15|archive-date=2021-12-15|archive-url=https://web.archive.org/web/20211215020857/https://www.techpowerup.com/review/intel-core-i5-10400f/|url-status=live}}</ref> on the BCLK.