27 inch i7 high pitch noise when at full brightness

Discussion in 'iMac' started by Harpy007, Nov 18, 2009.

  1. Harpy007 macrumors regular

    Dec 31, 2006
    Hi there!

    I just received my new iMac yesterday and I'm having what many users from the Apple Discussion Forums are reporting: when my computer is at full brightness, I can hear a high pitch noise. It is not that loud but when I lower the brightness, the noise goes down considerably.

    The problem is, I have a BTO iMac i7 and I'm wondering if my problem is isolated for the newest batch and if I should get a replacement. So, do any of you with a i7 getting the high pitch noise?

    BTW, this is the link to the Apple Discussion:


    Thanks for you input
  2. nicroma macrumors 6502a


    Jun 20, 2009
    Midwest, USA
    My iMac does not emit a high pitched sound at any brightness. I just positioned my ears at different places around my iMac and changed the brightness to listen. My room is totally silent right now and I have good hearing.
  3. Harpy007 thread starter macrumors regular

    Dec 31, 2006
    Thanks for your input

    This morning when I turned on the computer, there was no noise whatsoever and it's only then that I realised that the noise only starts when the computer is on for more than 30 minutes. So that means when the computer gets hot, the noise starts and it keeps doing it until I shutdown the system.

    I'm still wondering if this problem is something that could be fixed via firmware update since a lot of people reported the same noise. What would you guys do? I don't really like paying 3000$ for a machine that is not perfect... :(
  4. Harpy007 thread starter macrumors regular

    Dec 31, 2006
    Yeah I think I'm going to ring Apple Care tonight... the more I hear it, the more I think this isn't normal. I'll keep you guys posted in case someone else have the same issue.
  5. Gizmotoy macrumors 65816


    Nov 6, 2003
    Maybe the fan's making a strange noise when it's set to run at a low speed, such as might be the case after the computer's been running for 30 minutes or so.
  6. Harpy007 thread starter macrumors regular

    Dec 31, 2006
    Good point but I doubt the fan is responsible for the noise since the sound decrease when I lower the brightness. It's really an electronic noise like a electric static noise similiar to an old TV. What could be the cause? GPU? HD? CPU? My cat ;)
  7. Harpy007 thread starter macrumors regular

    Dec 31, 2006
    Called Apple and they told me this is nowhere near normal and I should bring it to an Apple tech. I have an appointment this week-end at my Apple Store, let's hope for the best.
  8. zerohp macrumors member

    Mar 6, 2008
    It's the power supply electronics. A lot of plasma TV's do it too.

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