The Advantages of Clocking a CPU

by Chris Hoffman
A computer's processor is seated on its motherboard.

A computer's processor is seated on its motherboard.

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A computer’s central processing unit, also known as its CPU, can be overclocked or underclocked. Overclocking involves the CPU’s clock rate above its manufacturer-specified default rate, and underclocking reduces the clock rate. The clock rate controls the amount of cycles the CPU performs each second, which affects the CPU’s performance. Underclocking and overclocking have advantages and disadvantages.


Overclocking increases a CPU’s performance. A CPU with a clock rate above the manufacturer’s specified rate performs more cycles per second. The additional clock cycles allow PC games and other demanding applications to run faster. A computer’s performance depends on more factors than its CPU speed, so increasing the clock rate helps only if the CPU is the system’s performance bottleneck. For example, a demanding 3-D game may be limited more by the computer’s graphics hardware than its CPU.


Underclocking reduces a CPU’s power consumption and heat generation. A CPU with a clock rate below the manufacturer’s specified rate performs fewer cycles per second. This causes the CPU to use less electricity, which is particularly useful for extending the battery life of laptops, smartphones and other mobile devices. Server administrators may also underclock servers and other systems that run for a long period of time and don’t require maximum performance, saving money on electricity. The CPU will also generate less heat, allowing it to be cooled easier. An underclocked CPU may not require a fan at all, allowing its computer to run silently.


Both overclocking and underclocking have disadvantages. Overclocking a CPU increases the CPU’s power consumption and causes it to generate more heat. The CPU needs better cooling, which consumes additional electricity. Overclocking a CPU can also void the CPU’s warranty and possibly cause heat damage, although newer CPUs reduce their clock speed or power off the computer before damage occurs. Underclocking a CPU reduces the CPU’s performance, which is the trade-off for reduced power consumption.


A CPU’s clock rate can be altered in a variety of ways. You can adjust a CPU’s clock rate from within the BIOS setup menu that you can access while booting a computer. Many computers, especially laptops and other mobile devices, automatically overclock and underclock the CPU itself to achieve maximum performance and the longest possible battery life. A CPU may be underclocked while idle and overclocked when a user launches a demanding computer game.

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