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The fan on my power supply has stopped blowing, is turning very slowly and not blowing hard, is making noises, or is only working intermittently

Explanation: The fan on the back of the power supply is malfunctioning, either permanently or intermittently.

Diagnosis: The most common cause of problems with the power supply fan is dirt that accumulates inside the fan. Sometimes cleaning the fan will fix the problem, but often it will not. The fan may also just wear out after a period of time. A fan that is working intermittently will eventually fail, usually within a few weeks.

Recommendation:

• Check carefully to make sure that the power supply fan is in fact the source of the noise. It may in fact be another component such as the CPU fan or (if you are unlucky) a hard disk drive. Many CPU fans are in fact quite noisy, and you may want to replace a noisy one with a quieter version if necessary.
• Clean the power supply fan using a PC vacuum or a can of compressed air. See if the noise goes away.
• If you just noticed this problem when you turned on the machine, wait a few minutes. It may go away as the fan comes up to speed. If it does, you might be able to just ignore this condition, but remember to check the fan regularly to make sure it is still working. The lack of sound can just as easily mean the fan has stopped turning altogether, which could lead to the power supply or PC itself overheating. It's safer to troubleshoot the fan even if the noise does stop, although I have had at least one PC make intermittent noise for a long time without the fan going dead.
• Replace the power supply fan, if you feel comfortable doing this.
• Replace the power supply, or take it in for servicing.

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