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Motherboard vs. Power Supply Failure: How to Tell the Difference

Motherboard vs. Power Supply Failure

A failed power supply and a failed motherboard can produce very similar symptoms, but with the right diagnostic equipment, determining the cause is usually straightforward.

Testing the Power Supply

When a computer is completely dead, I start by connecting the power supply to a dedicated power-supply tester. This allows me to check the PSU's output and quickly determine whether it is functioning correctly rather than trying to diagnose the problem based on symptoms alone.

A Failed Power Supply Can Damage the Motherboard

Finding a failed power supply doesn't necessarily mean I've found the computer's only problem. I've seen many cases where a power supply failure also damages the motherboard.

Once I've confirmed that the power supply has failed, I connect a known-good test power supply directly to the motherboard and attempt to start the system.

If the computer starts normally with the test power supply, I know the motherboard survived and the power supply is the component that needs to be replaced.

If the computer still won't start with a known-good power supply, the motherboard was likely damaged by the failure as well and will also need to be replaced.

Diagnose First, Replace Second

The important part is not guessing based on symptoms. I test the power supply independently and then verify the motherboard with a known-good power source. This allows me to determine what actually failed before recommending replacement parts.

Author: Richard Mallory, Home Net Computers

30+ Years of Professional IT Experience

**Home Net Computers** diagnoses power and motherboard issues for customers throughout the Greater Seattle Area — Bellevue, Redmond, Kirkland, Everett, and beyond. We'll test your system properly and tell you exactly what's wrong before any money is spent on parts. Call **206-478-5001** or reach out through our contact form to get a straight answer.