Overclocking in the context of computing devices refers to making them "run faster" than originally intended. More specifically it is the configuration of computer
The purpose of overclocking is to gain additional performance from a given component by increasing its operating speed. Normally, on modern systems, the target of overclocking is increasing the performance of a major chip or subsystem, such as the main processor or graphics controller, but other components, such as system memory (
While most modern devices are fairly tolerant of overclocking, all devices have finite limits, generally for any given voltage most parts will have a maximum "stable" speed where they still operate correctly. Past this speed the device starts giving incorrect results, which can cause malfunctions and sporadic behavior in any system depending on it. While in a PC context the usual result is a system crash, more subtle errors can go undetected, which over a long enough time can give unpleasant surprises such as
At this point an increase in operating voltage of a part may allow more headroom for further increases in clock speed, but increased voltage can also significantly increase heat output. At some point there will be a limit imposed by the ability to supply the device with sufficient power, the user's ability to cool the part, and the device's own maximum voltage tolerance before it achieves
The speed gained by overclocking depends largely upon the applications and workloads being run on the system, and what components are being overclocked by the user;
Conversely, the primary goal of
Underclocking is almost always involved in the latter stages of
Underclocking and undervolting would be attempted on a desktop system to have it operate silently (such as for a home entertainment center) while potentially offering higher performance than currently offered by low-voltage processor offerings. This would use a "standard-voltage" part and attempt to run with lower voltages (while attempting to keep the desktop speeds) to meet an acceptable performance/noise target for the build. This was also attractive as using a "standard voltage" processor in a "low voltage" application avoided paying the traditional price premium for an officially certified low voltage version. However again like overclocking there is no guarantee of success, and the builder's time researching given system/processor combinations and especially the time and tedium of performing many iterations of stability testing need to be considered. The usefulness of underclocking (again like overclocking) is determined by what processor offerings, prices, and availability are at the specific time of the build.
Overclocking has become more accessible with motherboard makers offering overclocking as a marketing feature on their mainstream product lines. However, the practice is embraced more by
Overclocking offers several draws for overclocking enthusiasts. Overclocking allows testing of components at speeds not currently offered by the manufacturer, or at speeds only officially offered on specialized, higher-priced versions of the product. A general trend in the computing industry is that new technologies tend to debut in the high-end market first, then later trickle down to the performance and mainstream market. If the high-end part only differs by an increased clock speed, an enthusiast can attempt to overclock a mainstream part to simulate the high-end offering. This can give insight on how over-the-horizon technologies will perform before they are officially available on the mainstream market, which can be especially helpful for other users considering if they should plan ahead to purchase or upgrade to the new feature when it is officially released.
Some hobbyists enjoy building, tuning, and "Hot-Rodding" their systems in competitive bench-marking competitions, competing with other like-minded users for high scores in standardized computer benchmark suites. Others will purchase a low-cost model of a component in a given product line, and attempt to overclock that part to match a more expensive model's stock performance. Another approach is overclocking older components to attempt to keep pace with increasing
Technically any component that uses a timer (or clock) to synchronize its internal operations can be overclocked. Most efforts for computer components however focus on specific components, such as,
Computer processors generally are overclocked by manipulating the
Any given component will ultimately stop operating reliably past a certain clock speed. Generally components will show some sort of malfunctioning behavior or other indication of compromised stability that alerts the user that a given speed is not stable, but there is always a possibility that a component will permanently fail without warning, even if voltages are kept within some pre-determined safe values. The maximum speed is determined by overclocking to the point of first instability, then accepting the last stable slower setting. Components are only guaranteed to operate correctly up to their rated values; beyond that different samples may have different overclocking potential. The end-point of a given overclock is determined by parameters such as available CPU multipliers, bus dividers,