freeCodeCamp/guide/english/computer-hardware/power-supply/index.md

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Power Supply

Power Supply

A Power Supply Unit (PSU) supplies power to a computer. It converts AC power into steady low-voltage DC power for the internal components. A power supply is required in order for a computer to operate properly and it's wattage must be matched appropriately to all the components inside the computer. It also regulates overheating by controlling the voltage. Depending on the model of power supply, voltage control can either be manual or automatic.

Description

Is typically seen as a metal box either in the top or bottom, most posterior portion of a PC case. It has a bunch of cables streaming out of it to various parts of the computer. These cables can be detachable or integrated depending on the model of PSU. Typically it's wattage (e.g 600w) is relative to the size of the PSU, and is an important factor to keep in mind when considering the demand of your machine vs how much space is inside the case.

Like the CPU, or RAM, the PSU is a necessary component to the PC because without it nothing within the machine would function. Arguably may be one of the more crucial parts to research when assembling custom computers because of this fact.

Modularity

PSUs can be divided into two categories:

Non-modular

A non-modular PSU is the most common type of PSU, this PSU is unadaptable with the power ports it provides to the components, it will usually contain:

  • A 32pin power supply module for the motherboard
  • Any number of SATA power supply modules, these are usually to power hard drives and disk drives
  • One or two PCIE power supply modules, usually for expansion cards such as GPU
  • A CPU power supply module

Modular

Modular power supplies are becoming more common nowadays, these are more commonly seen amongst "high end" PSUs. The advantage these have over non-modular supplies is that they can be expanded to add additional power supply modules.

As with the non-modular supply, you will get:

  • A 32 pin power supply module for the motherboard
  • a CPU power supply module, this will usually be on the same cable as the motherboard power

The PSU will then have several expansion slots on the back to add additional PCIE power cables and SATA cables for multi GPU or hard drive builds.

A PSU is usually not user-serviceable. For your safety, it is wise to never open a power supply unit.

Note: Please do not "cheap out" when buying a power supply, it is one of the most crucial elements when building a PC and can damage your other components if not treated as such.

Standard types of Cables

With every modern power supply you should have:

  • 1x Large cable for motherboard
  • 1x Small cable for motherboard, typically powers the CPU
  • 1x Small cable to power the GPU
  • 2x or more small cables to power hard drives, optical drives, and accessory parts.

MISC Information

Because the power supply unit is the first component between the electric outlet and your other PC parts, they are at the highest risk of damage from power surges or spikes. If your machine is situated in an area where these things are common, it would be wise to invest in a surge protector or similar piece of hardware to prevent that kind of damage. Additionally, the internal parts of a PSU are usually not user serviceable. For your safety, it is wise to never open a power supply unit without proper equipment and/or certifications.

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