Computer Hardware

PSU

Definition

A Power Supply Unit (PSU) is a component that converts the AC power from a wall outlet into the regulated low-voltage DC power required by the internal components of a computer.

Why It Matters

The PSU is the heart of the computer, providing the necessary power to every single component. A stable and reliable PSU is critical for system stability. An inadequate or faulty PSU can cause crashes and damage components.

Contextual Example

A high-end gaming PC with a powerful CPU and GPU requires a PSU with a high wattage rating (e.g., 850W or more) to supply enough power under heavy load.

Common Misunderstandings

  • PSU efficiency is measured by an "80 Plus" rating (e.g., Bronze, Gold, Platinum), which indicates how much AC power is converted to DC power versus being lost as heat.
  • Modular PSUs have detachable cables, which makes cable management inside the computer case much cleaner.

Related Terms

Last Updated: December 17, 2025