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Power Supply Overview

A power supply is an essential component within a computer; no internal computer device works without it. The power supply converts AC to DC, distributes lower-voltage DC power to components throughout the computer, and provides cooling through the use of a fan located inside the power supply. The AC voltage a power supply accepts is normally either 100 to 120 volts or 200 to 240 volts. Some dual-voltage power supplies can accept either. This type of power supply can have a selector switch on the back or can automatically detect the input voltage level. The power supply is sometimes a source of unusual problems. The effects of the problems can range from those not noticed by the user to those that shut down the system.

There are two basic types of power supplies: switching and linear. A computer uses a switching power supply. It provides efficient power to all the computer’s internal components (and possibly to some external ones, such as USB devices). It also generates minimum heat, comes in small sizes, and is cheaper than linear power supplies. A switching power supply requires a load (something attached to it) in order to operate properly. With today’s power supplies, a motherboard is usually a sufficient load, but a technician should always check the power supply specifications to be sure.

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