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Strange noise from PSU on start up

By terry5880
Mar 6, 2012
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  1. Hi all made thread about this before but wasnt sure where it was coming from iu now know its def the psu its a 750watt .. and fo0r months now when i 1st start pc it makes like a whirling grinding noise quite loud so i have to turn off then back on and always the 3rd time it will stop and work fine. sometimes i get to desktop and no icons so have to press little restart button but then ok and only when cold as if been on a while and i restart or turn off and on it dont do it do i need to buy new 1 or is there a fix for it cheers
  2. Cinders

    Cinders TechSpot Chancellor Posts: 1,313   +12

    The fan in the PSU is the only thing that usually makes noise. I can't in good faith recommend that you replace the fan in your PSU because even an unplugged PSU can generate enough voltage to KILL you. Please get a new PSU instead.
  3. dmill89

    dmill89 TS Guru Posts: 737

    Of course there is a fix for it, it just depends on how involved it may be and whether the PSU is even worth trying to fix. What is the brand and model of the PSU, what are the ratings on the individual rails? Is the noise coming from the fan or is it something else? And of course if it is anything but the fan which is a simple fix what are your soldering / electronics repair skills, and what if any soldering / diagnostic (multi-meter, oscilloscope, etc.) do you have? I would not recommend any major PSU repair to anyone who does not have skills and experience in repairing electronics. Doing it wrong can fry all the attached components or even start a fire.

    Here is a link to a write-up I did on a Free with case, "Semi-Gutless Wonder" PSU that I rebuilt and upgraded to give you an idea of what might be involved.
    http://www.badcaps.net/forum/showthread.php?t=18895

    Again I do not recommend such a repair to anyone without the skills, knowledge, and tools to complete it properly and safely
  4. dmill89

    dmill89 TS Guru Posts: 737


    Most PSUs have bleed resistors that will drain the main caps in a few minutes so this danger is largely overstated. Just don't try to work on a PSU right after you unplug it, or better yet unplug it and turn it on either by pressing the power button with it unplugged while it is still in the PC or jumpering the green wire on the ATX connector to any black wire while out of the PC to ensure it is drained. Measuring the voltage across the main caps with a DMM will show if they still have a charge.

    Again repairs should only be conducted by someone with the skills and tools to accomplish it safely.


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