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How to Install a Desktop Power Supply

Swapping power supplies is straightfoward on desktop machines

By Mark Kyrnin Mark Kyrnin Writer University of California, Berkeley Mark Kyrnin is a former Lifewire writer and computer networking and internet expert who also specializes in computer hardware. lifewire's editorial guidelines Updated on June 4, 2022 Tweet Share Email Tweet Share Email Accessories & Hardware The Quick Guide to Webcams Keyboards & Mice Monitors Cards HDD & SSD Printers & Scanners Raspberry Pi

What to Know

Open case > align PSU mounting holes > fasten to case > set voltage > plug into motherboard > connect power.Caution: Turn off and disconnect computer from power before opening. Never insert metal objects into PSU vents. This article explains how to install a basic desktop computer power supply unit (PSU) to supply power and regulate heating.

How to Install a Power Supply

Follow these steps to set up and install a basic power supply unit. Many name-brand manufacturer PCs integrate specially designed power supplies that have been built for their systems. As a result, it's generally not possible to buy a replacement power supply and install it into these systems. If your power supply has problems, contact the manufacturer for repairs or a replacement. Open the case. The method for opening the case varies depending on its design. Most new cases use either a panel or a door. Older computers require the whole cover to be removed. Remove any screws fastening the cover to the case and set the screws aside. All power supplies contain capacitors that retain power after the power supply is turned off. Never open or insert any metal objects into the vents of the power supply, as you risk electrical shock. Align the PSU in the case so that the four mounting holes align properly. Verify that any air-intake fan on the power supply faces toward the center of the case and not toward the case cover. Fasten the power supply. Hold the PSU in position while you screw it into the case. Set the voltage switch. Verify that the voltage switch on the back of the power supply is set to the proper voltage level for your country. North America and Japan use 110/115v. Europe and other ​countries use 220/230v. Plug the power supply into the motherboard. If the computer has the motherboard installed into it, connect the power leads to the motherboard. Most modern motherboards use the large ATX power connector that is plugged into the socket on the motherboard. Some motherboards require an additional amount of power through a four-pin ATX12V connector. Connect power to the devices. Many items in a computer case require power from the power supply. Typically, these devices use the four-pin Molex style connector. Locate the appropriately sized power leads and plug the leads into any devices that require power. Replace the computer cover or return the panel to the case. Fasten the cover or panel with the screws that were removed when you opened the case. Plug in the power and turn on the computer. Plug in the power supply AC cord and turn the switch on the power supply to the ON position. The computer system should have available power and can be powered on. Was this page helpful? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Subscribe Tell us why! Other Not enough details Hard to understand Submit More from Lifewire How to Use a Power Supply Tester to Test a PSU Power Supply Voltage Tolerances How to Manually Test a Power Supply With a Multimeter How to Control the CPU Fan on Windows 10 What is a PSU? What is an ATX Power Supply? How to Open a Desktop Computer Case How to Install a Graphics Card How to Install a Second SSD How to Unscrew and Reseat Expansion Cards How to Reseat a Desktop Memory Module ATX Power Supply Pinout Tables How to Fix a Computer That Turns on but Displays Nothing 24-pin Motherboard Power Connector Pinout 15-Pin SATA Power Connector Pinout How to Fix a Computer That Turns On and Then Off How to Reseat Internal Data and Power Cables Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. Cookies Settings Accept All Cookies