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Overclocking is the practice of modifying a component's settings to run at a higher clock speed than the manufacturer's specification. The idea is to increase performance for free, but it usually comes at the cost of stability.

Overclocking is commonly practiced by PC enthusiasts to squeeze the most performance out of their machines. Some enthusiasts will do this so they can buy a lower-end system, overclock it, and achieve the performance of a higher-end system. The price of overclocking is the need for more efficient cooling than that which came with the processor, and overclockers have sometimes resorted to extremely elaborate cooling methods such as water coolers or refrigerated computer cases. Overclocking is done at the enthusiast's own risk, with the possibilities of burning the microprocessor or losing system stability as real dangers.

Commonly overclocked components include:CPUs, video cards, motherboard chipsets, and RAM. Methods that have been used to cool overclocked components include: forced convection, literally a fan blowing on a surface; water cooling, which is similar to how automobile engines are cooled; liquid nitrogen, which is perhaps the most dangerous method; phase change cooling, which is how a refrigerator works; and submersion, which puts the entire computer in an inert fluid. (Mineral oil is the cheapest, and thus most common.)

Overclocking arises in part by the manufacturing processes of CPU's. In many cases, CPU's with different rated clock speeds are manufactured via exactly the same process. The CPU's are tested and the clock speed that the CPU is marketed under is the speed at which the CPU has been tested to operate consistently well. Overclocking trades stability for performance. In addition, there have been situations in which a chip manufacturer will deliberately underrate a chip to respond to marketing pressures. The Intel Celeron 300A is probably the most famous example of this; introduced in July of 1998, the chip was easily overclocked from its rated 300 MHz to a speed of 450 MHz simply by using a 100 MHz Front side bus motherboard designed for the Pentium II processor.


An overclocker is generally defined as someone who overclocks his or her computer. The term overclocker has grown to include a wider group of people. In some ways overclockers have grown into a group of computer modifiers, known as computer modders. The two are closely related. As overclockers brought extreme forms of overclocking to their computers, computer modders took what they did and improved upon it by creating aesthetically appealing computers that are overclocked as well.

Overclocking today is not as prevalent as it once was. Microprocessors are becoming speedy enough as manufactured, and the tremendous heat produced by modern processors limits the amount of overclocking that can be stably achieved.

Commonly overclocked CPUs

Several models of CPU from both Intel and AMD have become famous in the enthusiast community for their ability to overclock to speeds up to 25-50 percent above stock. The best known examples include:

See also CPU locking, Front side bus, Underclocking