How to Test Your PSU: A Step-by-Step Guide

How to Test Your PSU: A Step-by-Step Guide


Testing your PSU (Power Supply Unit) is crucial to ensure the stability and reliability of your computer system. A malfunctioning PSU can cause various issues, from random shutdowns to hardware failures. In this step-by-step guide, we will walk you through the process of testing your PSU to identify any potential problems and prevent them from causing further damage.

Step 1: Safety First

Before starting the testing process, it is important to prioritize your safety. Make sure to disconnect the power cord from the wall outlet and turn off your computer completely. Avoid working on a carpeted surface and use an anti-static wrist strap if available to prevent any damage from electrostatic discharge.

Step 2: Gathering the Necessary Tools

To properly test your PSU, you will need a few essential tools: a digital multimeter, a paperclip or wire, and a reliable power supply tester (optional). The digital multimeter will be used to measure the voltage output of your PSU, while the paperclip or wire will help simulate the PSU’s power-on signal.

Step 3: Testing the PSU with a Multimeter

1. Locate the 24-pin ATX power connector on your motherboard and disconnect it from the PSU.
2. Connect the black (ground) probe of the multimeter to any black wire in the 24-pin ATX connector and the red (voltage) probe to the yellow wire. This will measure the +12V rail.
3. Turn on the power to your PSU by either switching on the power supply tester (if available) or by shorting the green wire with any black wire in the 24-pin ATX connector using the paperclip or wire.
4. Check the multimeter reading for the +12V rail. A value within ±5% of the rated voltage indicates a healthy PSU.

Repeat the above steps for the +5V and +3.3V rails as well, using the red and orange wires respectively in the 24-pin ATX connector. Again, ensure the multimeter readings are within the acceptable range.

Step 4: Additional PSU Tests (Optional)

While the multimeter test provides a good overall assessment of your PSU, you can also consider using a power supply tester for more detailed results. A power supply tester is specifically designed to analyze various PSU functions, such as voltage output, fan functionality, and power-on self-test (POST).

Simply connect your PSU to the power supply tester following the manufacturer’s instructions and observe the provided LED indicators or LCD display for any abnormalities. This can give you a more comprehensive understanding of your PSU’s overall health.


Testing your PSU is a crucial step in troubleshooting computer issues and ensuring the stability of your system. By following this step-by-step guide, you can easily identify any potential problems with your PSU and take appropriate actions to prevent further damage. Remember to prioritize safety, gather the necessary tools, and perform the tests accurately. Regularly testing your PSU can save you from unexpected hardware failures and ensure your computer runs smoothly for years to come.