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[ The PC Guide | Troubleshooting and Repair Guide | The Troubleshooting Expert | Troubleshooting Specific Components | Troubleshooting Power Sources and Power Protection Devices ]

There's a squealing or whining sound coming from the power supply when I turn it on

Explanation: The PC is making a squealing or whining sound, coming from the back of the power supply unit. The sound may be louder when the PC is first started up, and then diminish, or it may get worse as the PC is left on for a period of time.

Diagnosis: Usually, the cause of this problem is the fan on the back of the power supply. It will tend to accumulate dirt over time, and cheaper ones will fail readily. If the fan is making noise now, it will probably fail soon. This usually takes years, but with cheaper power supplies that can be a surprisingly small number of years. Rarely, the problem can be with the internals of the power supply itself.


  • Look and listen closely at the back of the PC to see if the fan is what is causing the problem. If it appears that the fan is making the noise, troubleshoot it here.
  • If you hear a high-pitched whistling sound, this could be coming from components within the power supply. This will require you to either replace the power supply or take the system in for service.

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