iMac 27 HDD knocking/tapping sound

Discussion in 'iMac' started by swee5420, May 22, 2010.

  1. swee5420 macrumors member

    Feb 10, 2010
    I don't know whether this has been shared by other users or not, but just in case.

    So, i have experienced some noise from the imac, some weird sond like someone is knocking the case inside my imac, and it happens once in a few minutes. The 1st thing comes to my mind is the HDD, so i check the forum about the issue, and yes they are many people experienced this problem.

    At first, I tried to investigate what is triggering the sound, is it random or is it due to the HDD being stress by spotlight or other stuff. But i found out that it only happen when my system is under minimal usage, ie surfing net, or writing in Xcode.

    My conclusion comes to when the HDD is not being used, it will trigger that sound, and I think it may due to the HDD is going into sleep mode which trigger the sound.

    I ran an experiment by opening my utorrent and let it start downloading and stress the HDD continuously, surprisingly i did not hear the noise anymore, not until i exit my utorrent.

    So, I think the sound is actually produce by the HDD when it is going into sleep mode to save power when not being used. The option to solve the problem is either let your HDD run continuously to prevent it from sleeping, or just ignore the sound.

    I am sure there is some kind of technique that can turn the HDD power save mode off, if anyone did find it, do kindly post here:)
  2. glitch44 macrumors 65816

    Feb 28, 2006
    I'd be concerned about any noise like that coming from my hard drive, as it could be an indication of imminent failure. Personally, I'd take it back to the Apple store to get it replaced.
  3. PsychOfMSE macrumors member

    May 22, 2010
    The first time I heard a knocking sound coming from my HD I would immediately back-up everything I possibly could.

    If you're under warranty take that thing in ASAP and get a replacement.

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