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Message: <blockquote data-quote="nightshadow129" data-source="post: 1021929" data-attributes="member: 60472">Overclocking??Overclocking                      From Wikipedia, the free encyclopediaOverclocking is the process of forcing a <a href="http://en.wikipedia.org/wiki/Computer_hardware" target="_blank">computer component</a> to run at a higher <a href="http://en.wikipedia.org/wiki/Clock_rate" target="_blank">clock rate</a> than it was designed for or was designated by the manufacturer, usually practiced by <a href="http://en.wikipedia.org/wiki/Personal_computer" target="_blank">personal computer</a> enthusiasts in order to increase the performance of their computers. Some of them purchase low-end computer components which they then overclock to higher speeds, or overclock high-end components to attain levels of performance beyond their factory defaults. Others overclock outdated components to keep pace with new <a href="http://en.wikipedia.org/wiki/System_requirements" target="_blank">system requirements</a>, rather than purchasing new hardware products as expected by the <a href="http://en.wikipedia.org/wiki/Computer_industry" target="_blank">computer industry</a>. Users who overclock their components mainly focus their efforts on <a href="http://en.wikipedia.org/wiki/Central_processing_unit" target="_blank">processors</a>, <a href="http://en.wikipedia.org/wiki/Video_card" target="_blank">video cards</a>, <a href="http://en.wikipedia.org/wiki/Motherboard" target="_blank">motherboard</a> <a href="http://en.wikipedia.org/wiki/Chipset" target="_blank">chipsets</a>, and <a href="http://en.wikipedia.org/wiki/Random_Access_Memory" target="_blank">Random Access Memory (RAM)</a>. It is done through manipulating the <a href="http://en.wikipedia.org/wiki/CPU_multiplier" target="_blank">CPU multiplier</a> and the motherboard's <a href="http://en.wikipedia.org/wiki/Front_side_bus" target="_blank">front side bus</a> (FSB) speed until a maximum stable operating frequency is reached. While the idea is simple, variation in the electrical and physical characteristics of computing systems complicates the process. CPU multipliers, bus dividers, <a href="http://en.wikipedia.org/wiki/Voltage" target="_blank">voltages</a>, thermal loads, cooling techniques and several other factors can affect it.   Considerations There are several considerations when overclocking. The first consideration is to ensure that it is supplied with adequate power to operate at the new speed. However, supplying the power with improper settings or applying excessive <a href="http://en.wikipedia.org/wiki/Voltage" target="_blank">voltage</a> can permanently damage a component. Since tight tolerances are required for overclocking, only more expensive motherboards—with advanced settings that computer enthusiasts are likely to use—have built-in overclocking capabilities. Motherboards with fewer settings, such as those found in <a href="http://en.wikipedia.org/wiki/Original_Equipment_Manufacturer" target="_blank">Original Equipment Manufacturer</a> (OEM) systems, lack such features in order to eliminate the possibility of misconfiguration by an inept user and cut down on the support costs and warranty claims to the manufacturer.  Cooling   <a href="http://en.wikipedia.org/wiki/Image:Copper_heat_sink_with_pipes.jpg" target="_blank"><img src="http://upload.wikimedia.org/wikipedia/en/thumb/4/47/Copper_heat_sink_with_pipes.jpg/180px-Copper_heat_sink_with_pipes.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a>  <a href="http://en.wikipedia.org/wiki/Image:Copper_heat_sink_with_pipes.jpg" target="_blank"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a>   All <a href="http://en.wikipedia.org/wiki/Electrical_network" target="_blank">electronic circuits</a> discharge heat generated by the movement of <a href="http://en.wikipedia.org/wiki/Electron" target="_blank">electrons</a>. As clock frequencies in <a href="http://en.wikipedia.org/wiki/Digital_circuit" target="_blank">digital circuits</a> increase, the temperature goes up. Due to increased heat produced by overclocked components, an effective cooling system is necessary to avoid damaging the hardware. In addition, digital circuits slow down at high temperatures due to changes in <a href="http://en.wikipedia.org/wiki/MOSFET" target="_blank">metal–oxide–semiconductor field-effect transistor</a> (MOSFET) device characteristics. Wire resistance also increases slightly at higher temperatures, contributing to decreased circuit performance. Because most stock cooling systems are designed for the amount of heat produced during non-overclocked use, overclockers typically turn to more effective cooling solutions, such as powerful <a href="http://en.wikipedia.org/wiki/Fan_%28mechanical%29" target="_blank">fans</a> or heavy duty <a href="http://en.wikipedia.org/wiki/Heatsinks" target="_blank">heatsinks</a>. Size, shape, and material all influence the ability of a heatsink to dissipate heat. Efficient heatsinks are often made entirely of thermally conductive <a href="http://en.wikipedia.org/wiki/Copper" target="_blank">copper</a>, but these are usually expensive.<a href="http://en.wikipedia.org/wiki/Overclocking#_note-Wainner38" target="_blank">[3]</a> <a href="http://en.wikipedia.org/wiki/Aluminum" target="_blank">Aluminum</a> is more widely used material for heatsinks, being cheaper than copper. <a href="http://en.wikipedia.org/wiki/Cast_iron" target="_blank">Cast iron</a> is the least expensive, but has poor <a href="http://en.wikipedia.org/wiki/Thermal_conductivity" target="_blank">thermal conductivity</a>. Many good-quality heatsinks combine two or more materials to maximize thermal conductivity while minimizing cost.<a href="http://en.wikipedia.org/wiki/Overclocking#_note-Wainner38" target="_blank"></a><a href="http://en.wikipedia.org/wiki/Overclocking#_note-Wainner38" target="_blank"></a>  <a href="http://en.wikipedia.org/wiki/Image:DIY_watercooling_T-Line.JPG" target="_blank"><img src="http://upload.wikimedia.org/wikipedia/en/thumb/7/7b/DIY_watercooling_T-Line.JPG/180px-DIY_watercooling_T-Line.JPG" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a>  <a href="http://en.wikipedia.org/wiki/Image:DIY_watercooling_T-Line.JPG" target="_blank"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a> Interior of a water cooled computer, showing CPU <a href="http://en.wikipedia.org/wiki/Water_block" target="_blank">water block</a>, tubing and pump   <a href="http://en.wikipedia.org/wiki/Water_cooling" target="_blank">Water cooling</a> and passive <a href="http://en.wikipedia.org/wiki/Coolant" target="_blank">liquid coolant</a> carrying <a href="http://en.wikipedia.org/wiki/Waste_heat" target="_blank">waste heat</a> to a radiator, which is similar to an <a href="http://en.wikipedia.org/wiki/Automobile_engine" target="_blank">automobile engine</a>'s cooling system, provide more effective cooling than heatsink and fan combinations when properly implemented, because liquid is denser than air and therefore offers greater thermal transference. <a href="http://en.wikipedia.org/wiki/Thermoelectric_cooling" target="_blank">Thermoelectric cooling</a> devices, also known as Peltier devices, are recently popular with the onset of high <a href="http://en.wikipedia.org/wiki/Thermal_Design_Power" target="_blank">Thermal Design Power</a> (TDP) processors made by Intel and AMD. Thermoelectric cooling devices create temperature differences between two plates by running an <a href="http://en.wikipedia.org/wiki/Electric_current" target="_blank">electric current</a> through the plates. This method of cooling is highly effective but has a drawback that it leads to a lot of excess heat. For this reason, it is often necessary to supplement thermoelectric cooling devices with a convection-based heatsink or a water cooling system.  <a href="http://en.wikipedia.org/wiki/Image:2007Computex_Day2_Hall2-23.jpg" target="_blank"><img src="http://upload.wikimedia.org/wikipedia/commons/thumb/d/df/2007Computex_Day2_Hall2-23.jpg/180px-2007Computex_Day2_Hall2-23.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a>  <a href="http://en.wikipedia.org/wiki/Image:2007Computex_Day2_Hall2-23.jpg" target="_blank"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a> <a href="http://en.wikipedia.org/wiki/Liquid_nitrogen" target="_blank">Liquid nitrogen</a> may be used for cooling an overclocked system, when an extreme measure is needed.Other cooling methods are <a href="http://en.wikipedia.org/wiki/Forced_convection" target="_blank">forced convection</a> and <a href="http://en.wikipedia.org/wiki/Phase_change" target="_blank">phase change</a> cooling which is used in <a href="http://en.wikipedia.org/wiki/Refrigerator" target="_blank">refrigerators</a>. <a href="http://en.wikipedia.org/wiki/Liquid_nitrogen" target="_blank">Liquid nitrogen</a>, <a href="http://en.wikipedia.org/wiki/Liquid_helium" target="_blank">liquid helium</a> and <a href="http://en.wikipedia.org/wiki/Dry_ice" target="_blank">dry ice</a> are used as coolants in extreme measures,<a href="http://en.wikipedia.org/wiki/Overclocking#_note-Wainner44" target="_blank">[4]</a> such as record-setting attempts or one-off experiments rather than cooling an everyday system. These extreme methods are generally impractical in the long term, as they require refilling reservoirs of vaporizing coolant and <a href="http://en.wikipedia.org/wiki/Condensation" target="_blank">condensation</a> is formed on components due to difference between component temperature and air temperature.<a href="http://en.wikipedia.org/wiki/Overclocking#_note-Wainner44" target="_blank">[4]</a> Moreover, <a href="http://en.wikipedia.org/wiki/Silicon" target="_blank">silicon</a>-based <a href="http://en.wikipedia.org/wiki/Junction_gate_field-effect_transistor" target="_blank">junction gate field-effect transistors</a> (JFET) will degrade below temperatures of roughly 100 <a href="http://en.wikipedia.org/wiki/Kelvin" target="_blank">K</a> (−173 <a href="http://en.wikipedia.org/wiki/Celsius" target="_blank">°C</a>/−280 <a href="http://en.wikipedia.org/wiki/Fahrenheit" target="_blank">°F</a>) and eventually cease to function or "freeze out" at 40 K (−233 °C/−388 °F),<a href="http://en.wikipedia.org/wiki/Overclocking#_note-2" target="_blank">[5]</a> so using extremely cold coolants may cause devices to fail.    Submersion cooling, used for <a href="http://en.wikipedia.org/wiki/Cray-2" target="_blank">Cray-2</a> <a href="http://en.wikipedia.org/wiki/Supercomputer" target="_blank">supercomputer</a>, involves sinking a part of computer system directly into a chilled liquid substance that is thermally conductive but sufficiently low in <a href="http://en.wikipedia.org/wiki/Electrical_conductivity" target="_blank">electrical conductivity</a>. The advantage of this technique is that no condensation can form on components.<a href="http://en.wikipedia.org/wiki/Overclocking#_note-Wainner48" target="_blank">[6]</a> A good submersion liquid is <a href="http://en.wikipedia.org/wiki/Fluorinert" target="_blank">Fluorinert</a> made by <a href="http://en.wikipedia.org/wiki/3M" target="_blank">3M</a>, which is expensive and requires permits to purchase it. Another option is <a href="http://en.wikipedia.org/wiki/Mineral_oil" target="_blank">mineral oil</a>, but any impurities like water or scenting agents might cause it to conduct electricity.<a href="http://en.wikipedia.org/wiki/Overclocking#_note-Wainner48" target="_blank">[6]</a>  Stability and functional correctness As an overclocked component operates outside of the manufacturer's recommended operating conditions, it may function incorrectly, leading to system instability. An unstable overclocked system, while it may work fast, can be frustrating to use. Another risk is <a href="http://en.wikipedia.org/wiki/Reliability%2C_Availability_and_Serviceability" target="_blank">silent data corruption</a>—errors that are initially undetected. In general, overclockers claim that testing can ensure that an overclocked system is stable and functioning correctly. Although software tools are available for testing hardware stability, it is generally impossible for anyone (even the processor manufacturer) to thoroughly test the functionality of a processor. A particular "stress test" can verify only the functionality of the specific instruction sequence used in combination with the data and may not detect faults in those operations. For example, an arithmetic operation may produce the correct result but incorrect <a href="http://en.wikipedia.org/wiki/Status_register" target="_blank">flags</a>; if the flags are not checked, the error will go undetected. Achieving good <a href="http://en.wikipedia.org/wiki/Fault_coverage" target="_blank">fault coverage</a> requires immense engineering effort, and despite all the resources dedicated to validation by manufacturers, mistakes can still be made. To further complicate matters, in process technologies such as <a href="http://en.wikipedia.org/wiki/Silicon_on_insulator" target="_blank">silicon on insulator</a>, devices display <a href="http://en.wikipedia.org/wiki/Hysteresis" target="_blank">hysteresis</a>—a circuit's performance is affected by the events of the past, so without carefully targeted tests it is possible for a particular sequence of state changes to work at overclocked speeds in one situation but not another even if the voltage and temperature are the same. Often, an overclocked system which passes stress tests experiences instabilities in other programs.<a href="http://en.wikipedia.org/wiki/Overclocking#_note-3" target="_blank">[7]</a> In overclocking circles, "stress tests" or "torture tests" are used to check for correct operation of a component. These workloads are selected as they put a very high load on the component of interest (e.g. a graphically-intensive application for testing video cards, or a processor-intensive application for testing processors). Popular stress tests include <a href="http://en.wikipedia.org/wiki/Prime95" target="_blank">Prime95</a>, <a href="http://en.wikipedia.org/wiki/Super_PI" target="_blank">Super PI</a>, <a href="http://en.wikipedia.org/w/index.php?title=SiSoftware_Sandra&action=edit" target="_blank">SiSoftware Sandra</a>, <a href="http://en.wikipedia.org/wiki/BOINC" target="_blank">BOINC</a>, Intel Thermal Analysis Tool and <a href="http://en.wikipedia.org/wiki/Memtest86" target="_blank">Memtest86</a>. The hope is that any functional-correctness issues with the overclocked component will show up during these tests, and if no errors are detected during the test, the component is then deemed "stable". Since fault coverage is important in <a href="http://en.wikipedia.org/wiki/Software_testing" target="_blank">stability testing</a>, the tests are often run for long periods of time, hours or even days.  Factors allowing overclocking Overclockability arises in part due to the economics of the manufacturing processes of CPUs. In most cases, CPUs with different rated clock speeds are manufactured via exactly the same process. The clock speed that the CPU is rated for is at or below the speed at which the CPU has passed the manufacturer's functionality tests when operating in worst-case conditions (for example, the highest allowed temperature and lowest allowed supply voltage). Manufacturers must also leave additional margin for reasons discussed below. Sometimes manufacturers have an excess of similarly high-performing parts and cannot sell them all at the flagship price, so some are marked as medium-speed chips to be sold for medium prices. The performance of a given CPU <a href="http://en.wikipedia.org/wiki/Stepping_%28version_numbers%29" target="_blank">stepping</a> usually does not vary as widely as the marketing clock levels[<a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" target="_blank">citation needed</a>]. When a manufacturer rates a chip for a certain speed, it must ensure that the chip functions properly at that speed over the entire range of allowed operating conditions. When overclocking a system, the operating conditions are usually tightly controlled, making the manufacturer's margin available as free headroom. Other system components are generally designed with margins for similar reasons; overclocked systems absorb this designed headroom and operate at lower tolerances. Pentium architect <a href="http://en.wikipedia.org/wiki/Bob_Colwell" target="_blank">Bob Colwell</a> calls overclocking an "uncontrolled experiment in better-than-worst-case system operation".<a href="http://en.wikipedia.org/wiki/Overclocking#_note-4" target="_blank">[8]</a> Some of what appears to be spare margin is actually required for proper operation of a processor throughout its lifetime. As <a href="http://en.wikipedia.org/wiki/Semiconductor_device" target="_blank">semiconductor devices</a> age, various effects such as <a href="http://en.wikipedia.org/wiki/Hot_carrier_injection" target="_blank">hot carrier injection</a>, <a href="http://en.wikipedia.org/w/index.php?title=Negative_bias_thermal_instability&action=edit" target="_blank">negative bias thermal instability</a> and <a href="http://en.wikipedia.org/wiki/Electromigration" target="_blank">electromigration</a> reduce circuit performance. When overclocking a new chip it is possible to take advantage of this margin, but as the chip ages this can result in situations where a processor that has operated correctly at overclocked speeds for years spontaneously fails to operate at those same speeds later. If the overclocker is not actively testing for system stability when these effects become significant, errors encountered are likely to be blamed on sources other than the overclocking. Variance The extent to which a particular part will overclock is highly variable. Processors from different vendors, production batches, <a href="http://en.wikipedia.org/wiki/Stepping_%28version_numbers%29" target="_blank">steppings</a>, and individual units will all overclock to varying degrees.     Advantages <ul> <li data-xf-list-type="ul">The user can, in many cases, purchase a slower, cheaper component and overclock it to the speed of a more expensive component.</li> </ul> <ul> <li data-xf-list-type="ul">Faster performance in games, encoding, video editing applications, and system tasks at no additional expense, but at increased cost for electrical power consumption. Particularly for enthusiasts who regularly upgrade their hardware, overclocking can increase the time before an upgrade is needed.</li> </ul> <ul> <li data-xf-list-type="ul">Some systems have "bottlenecks", where small overclocking of a component can help realize the full potential of another component to a greater percentage than the limiting hardware is overclocked. For instance, many <a href="http://en.wikipedia.org/wiki/Motherboards" target="_blank">motherboards</a> with <a href="http://en.wikipedia.org/wiki/Athlon_64" target="_blank">AMD Athlon 64</a> processors limit the speed of four units of RAM to 333 <a href="http://en.wikipedia.org/wiki/Megahertz" target="_blank">MHz</a>. However, the memory speed is computed by dividing the processor speed (which is a base number times a <a href="http://en.wikipedia.org/wiki/CPU_multiplier" target="_blank">CPU multiplier</a>, for instance 1.8 GHz is most likely 9x200 MHz) by a fixed <a href="http://en.wikipedia.org/wiki/Integer" target="_blank">integer</a> such that, at stock speeds, the RAM would run at a clock rate near 333 MHz. Manipulating elements of how the processor speed is set (usually lowering the multiplier), one can often overclock the processor a small amount, around 100-200 MHz (less than 10%), and gain a RAM clock rate of 400 MHz (20% increase), realizing the full potential of the RAM.</li> </ul> <ul> <li data-xf-list-type="ul">Overclocking can be an engaging hobby in itself and supports many dedicated online communities. The <a href="http://en.wikipedia.org/wiki/PCMark" target="_blank">PCMark</a> website is one such site that hosts a leaderboard for the most powerful computers to be benchmarked using the program.</li> </ul>Disadvantages of overclocking performed incorrectly <ul> <li data-xf-list-type="ul">Increasing the operation frequency of a component will increase its thermal output in a linear fashion, while an increase in voltage causes a quadratic increase. Overly aggressive voltage settings or improper cooling may cause chip temperatures to rise so quickly that irreversible damage is caused to the chip causing immediate failure or significantly reducing its lifetime.</li> <li data-xf-list-type="ul">More common than hardware failure is functional incorrectness. Although the hardware is not permanently damaged, this is inconvenient and can lead to instability and <a href="http://en.wikipedia.org/wiki/Data_loss" target="_blank">data loss</a>. In rare, extreme cases entire <a href="http://en.wikipedia.org/wiki/Filesystem" target="_blank">filesystem</a> failure may occur, causing the loss of all data.<a href="http://en.wikipedia.org/wiki/Overclocking#_note-5" target="_blank">[9]</a></li> <li data-xf-list-type="ul">Improper installation of exotic cooling solutions like <a href="http://en.wikipedia.org/wiki/Watercooling" target="_blank">liquid</a> or <a href="http://en.wikipedia.org/wiki/Refrigeration_cycle" target="_blank">phase-change</a> cooling may result in failure of the cooling system, which may result in <a href="http://en.wikipedia.org/wiki/Water_damage" target="_blank">water damage</a> or damage to the processor due to the sudden loss of cooling.</li> </ul></blockquote>

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