how to test PC PSU

How To Test PC PSU | Comprehensive Guide

Spread the love

The Power Supply Unit (PSU) is a critical component of any computer system, responsible for supplying power to all other components. A faulty PSU can lead to system instability, random shutdowns, or even damage to other hardware components. Therefore, it’s essential to ensure that your PSU is functioning correctly. In this comprehensive guide, we’ll discuss various methods for how to test PC PSU to determine its health and reliability.

Understanding the Basics of a PSU:

Before delving into how to test a PC PSU, it’s crucial to have a basic understanding of how a PSU works. A PSU converts AC power from your wall outlet into DC power suitable for your computer’s components. It consists of various components, including transformers, capacitors, and voltage regulators, to ensure stable power delivery.

Signs of a Faulty PSU:

Before proceeding with testing, it’s essential to be aware of the signs that may indicate a faulty PSU:

  • Random system crashes or shutdowns.
  • Unexplained reboots or freezes.
  • Burning smells or unusual noises emanating from the PSU.
  • Inconsistent power delivery to components leads to performance issues.

Precautions Before Testing:

Before testing your PSU, it’s crucial to take some precautions to ensure your safety and prevent damage to your hardware:

  • Power off your computer and disconnect it from the electrical outlet.
  • Wait for a few minutes to allow the capacitors to discharge completely.
  • Use an anti-static wrist strap to prevent static discharge, especially if you’re handling sensitive components.
  • Handle the PSU and testing equipment with care to avoid electrical shocks.

Using a Power Supply Tester:

One of the simplest methods for testing a PSU is using a dedicated power supply tester. These testers come in various forms, from basic LED indicators to more advanced models with digital readouts. Here’s how to use a power supply tester:

  • Disconnect the PSU from your computer and all other components.
  • Plug the main 24-pin or 20+4-pin connector from the PSU into the corresponding slot on the tester.
  • Connect any additional power cables (CPU, GPU, SATA, etc.) to the appropriate slots on the tester.
  • Power on the PSU using the switch on the back or by momentarily connecting the green wire to any black wire on the 24-pin connector using a paperclip.
  • Observe the LED indicators or digital readout on the tester. They should indicate whether each voltage rail (3.3V, 5V, 12V) is within acceptable ranges.
  • If the tester indicates any abnormalities or if the PSU fails to power on, it may be faulty and require replacement.

Using a Multimeter:

Alternatively, you can use a multimeter to test the output voltages of your PSU manually. Here’s how to do it:

  • Set your multimeter to DC voltage mode and ensure it’s capable of measuring at least 20 volts.
  • Disconnect the PSU from your computer and all other components.
  • Locate the main 24-pin or 20+4-pin connector from the PSU.
  • Turn on your PSU using the switch on the back or by momentarily connecting the green wire to any black wire on the 24-pin connector using a paperclip.
  • Place the black probe (negative) of your multimeter on any black wire (ground) and the red probe (positive) on the corresponding colored wires to measure their voltages.
  • Refer to your PSU’s specifications to determine the acceptable voltage ranges for each rail (3.3V, 5V, 12V). Ensure that the measured voltages fall within these ranges.
  • If any voltage readings are significantly outside the acceptable ranges, it may indicate a faulty PSU.

Paperclip Test (Not Recommended for Novices):

The paperclip test is a rudimentary method for quickly determining whether a PSU powers on, but it does not provide information about the output voltages. Here’s how to perform the paperclip test:

  • Disconnect the PSU from your computer and all other components.
  • Locate the main 24-pin or 20+4-pin connector from the PSU.
  • Bend a paperclip into a U-shape and insert one end into the green wire (PSU_ON) pin and the other end into any black wire (ground) pin on the 24-pin connector.
  • Turn on your PSU using the switch on the back.
  • If the PSU’s fan spins up and any attached peripherals receive power, it indicates that the PSU is capable of turning on. However, this does not guarantee that it’s functioning correctly or providing stable power.

Observing for Visual Signs:

In some cases, visual inspection of the PSU can provide clues about its health. Look for the following signs:

  • Bulging or leaking capacitors.
  • Burn marks or discoloration on the PCB.
  • Unusual smells or noises coming from the PSU.
  • Excessive dust buildup, which can obstruct airflow and cause overheating.

Replacing the PSU:

If testing reveals that your PSU is faulty or if you suspect it’s causing issues with your computer, it’s recommended to replace it with a new one. When choosing a replacement PSU, consider factors such as wattage, efficiency rating, and compatibility with your system’s components.


Testing your PC PSU is an essential step in troubleshooting hardware issues and ensuring the stability and reliability of your computer system. Whether you use a dedicated power supply tester, or a multimeter, or perform a visual inspection, regularly checking your PSU’s health can help prevent unexpected failures and prolong the lifespan of your hardware. Remember to follow safety precautions and consult professional assistance if you’re unsure about performing any tests yourself.

FAQs About How To Test PC PSU:

Q. How do I safely disconnect my PSU?

A. Ensure your computer is off, unplug from the wall, and wait for capacitors to discharge before disconnecting cables.

Q. Can I test a PSU without removing it?

A. Yes, using a power supply tester or multimeter doesn’t require removing the PSU from your computer case.

Q. What if my PSU passes the test but my PC still won’t turn on?

A. Check other components like the motherboard, CPU, and RAM for issues that may prevent booting.

Q. Is it normal for a PSU to make noise?

A. Minimal noise from the PSU fan is normal, but any loud buzzing or clicking sounds could indicate a problem.

Q. Can I test a PSU without a load?

A. Yes, but keep in mind that a load test with components connected may provide a more accurate assessment of PSU health.

Last Updated on 14 February 2024 by Haleema

Haleema is an experienced PC builder

Haleema is an experienced PC builder who has been building PCs for the last couple of years. He has written several articles on PC components, including power supplies and graphics cards. In his articles, he explains how to check the compatibility of a power supply with a GPU and what things to consider when pairing them.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *