Types of PC Power Supply

By David Sandoval

Updated September 28, 2017

Whether you own a desktop or laptop, your computer needs to be powered somehow. Since a computer is full of different types of electronic circuits, though, several of which operate at different voltages, a simple connection to a wall outlet simply will not suffice. To convert the electricity coming from the wall to something that the computer can use, the system requires a power supply unit. Since the late 1990s, virtually all modern desktop computers use ATX multi-voltage power supplies to provide current to internal components.

Desktop Power Supplies

A power supply converts the Alternating Current (AC) electricity coming from your wall outlet into four voltage types that your computer commonly uses, all Direct Current (DC) power: - 5 volts, +5 volts, +12 volts and -12 volts. In addition to supplying the computer's power needs, a desktop computer's power supply also provides much-needed cooling with its power supply fan. Some computers (such as servers, gaming systems and high-end PCs) have multiple power supplies with multiple fans. This addresses two needs: the increased need for power due to high-speed or high-workload components, and increased cooling capacity, since high-speed and high-workload components generate a lot of heat.

Laptop Power Supplies

A laptop power supply is slightly different one used in a desktop computer. The job of converting electrical power from a wall socket into something a laptop can use is divided between two components: the external power adapter and the internal power supply. A laptop power adapter converts the electricity from a wall outlet to something the internal power supply can use. Typically this is a higher DC voltage than a desktop power supply furnishes. The adapter converts the power you get at the wall outlet and converts it to another voltage, often between 10 and 18 volts DC. From there, the internal power supply further converts the voltage to suit the needs of the computer.

Power Saving Modes

With advances in software and operating systems, so have computer power modes advanced. For instance, virtually all modern computers support "Power-Save" or "Sleep" mode. These modes enable you to turn off your computer with software rather than using the power button.

ATX Power Supplies

Features such as "Power Saving Mode" and "Sleep Mode" are made possible by ATX power supplies and compatible motherboards. When coupled with a compatible power supply, ATX motherboards support low-energy modes that enable temporary writing or caching of data while the computer is ""Hypernation" or "Sleep Mode."

ATX Supported Voltages

ATX power supplies support six voltage settings, which include +5 volt, -5 volt, +12 volt, -12 volt +5 volt standby, and +3.3 volt. This wide range of supported voltages provides manufacturers the flexibility needed to create peripherals and add-on components with varying current requirements.