PS, P/S, or PSU

Updated: 01/31/2019 by Computer Hope

PS, P/S, or PSU may refer to any of the following:

Computer power supply1. PS, P/S, or PSU are abbreviations for power supply or power supply unit. A power supply is a hardware component of a computer that supplies all components in a computer with power. The power supply converts a 110-115 or 220-230 volt AC (alternating current) into a steady low-voltage DC (direct current) usable by the computer and rated by the number of watts it generates. For example, the image to the right is an Antec True 330, a 330 Watt power supply.

Caution: Never open the casing of a power supply. It contains capacitors capable of holding a strong electrical charge, even if the computer is off and unplugged for an extended period of time.

Tip: You can protect your power supply and your computer from a surge and voltage drops by investing in a UPS. If you cannot afford a UPS, you should at the very least have the computer plugged into a surge protector.

Where is the power supply located in a computer?

In most computers, the power supply is located at the back of the computer. In a tower computer case, the power supply is usually located at the top back or bottom back of the case. In a desktop computer case, the power supply is located at the back left or back right of the case.

Parts found on the back of a power supply

Below is a list of parts you may find on the back of the power supply.

  • A connection for the power cord to the computer.
  • A fan opening to draw air and heat out of the power supply.
  • A red switch to change the power supply voltage.
  • A rocker switch to turn the power supply on and off.

On the front of the power supply, which is not visible unless the computer is opened, you will find several cables. These cables connect to the computer motherboard and other internal components. A power supply connects to the motherboard using an ATX style connector and may have one or more of the following cables to connect power to other devices.

Parts found inside a power supply

Below is a list of parts you will find inside a power supply.

  • A filter that smooths out the DC (direct current) coming from a rectifier.
  • A rectifier that converts AC (alternating current) into DC.
  • A transformer that controls the incoming voltage by stepping it up or stepping it down.
  • A voltage regulator that controls the DC output, allowing the correct amount of power, volts or watts, to be supplied to the computer hardware.

The order in which these internal power supply components function is as follows.

  1. Transformer
  2. Rectifier
  3. Filter
  4. Voltage Regulator

What items are powered by the computer PSU?

Everything contained in the computer chassis is powered by the power supply. For example, the motherboard, RAM, CPU, hard drive, and disc drive are all drawing power from the power supply. Some higher end video cards draw power directly from the power supply as well. Any other external devices and peripherals, such as the computer monitor and printer, have their own power source.

Note: If the computer is a laptop or an all-in-one computer, the display may also be powered by the computer power supply.

2. With Linux, ps is a command, see the ps command page for further information.

3. PS is short for PowerShell.

4. On a keyboard the Ps or Ps/SR key is short for the print screen key.

AC adapter, Computer acronyms, Hardware terms, Power cord, Power switch, Power terms, Redundant power supply, SMPS