27" 2017 iMac i5 Fan Noise

Discussion in 'iMac' started by iska, Aug 20, 2017.

  1. iska macrumors newbie

    Jun 12, 2017
    After a while of light use, my i5 iMac will turn on its fan. It's not loud, but you can definitely hear it. Once the fan is on, it stays on, even if the CPU is under 5% load for 10 minutes straight. If I put it in sleep mode and wake it back up, the fan noise is gone again. Until it seemingly randomly decides to start up again.

    I've read about fan noise problems with the i7 under load, but not about i5 idle fan noise. Is this a thing? Can I do anything to prevent it?
  2. Ph.D. macrumors 6502

    Jul 8, 2014
    Actually, the fan is always on, though it speeds up or slows down depending on the load. Its minimum speed is 1200 RPM.
  3. rlodina macrumors newbie


    Aug 14, 2017
    is i5 3.4Ghz, 3.5 or 3.8Ghz ?
  4. antonypg macrumors member

    May 8, 2008
    I have the top model i5 2017 and the fan has not been a problem. It runs at 1200 RPM, which I can just about hear in a silent room. If I run HandBrake to convert a movie then the fan slowly speeds up to around 1500 RPM, which is noticeable but still very quiet, and then drops back to 1200 RPM as soon as the encoding is finished.

    At one point I thought I could hear a very quiet high-pitch whine but it turned out to be an LED light bulb which I had just fitted in the room.
  5. bbnck macrumors 6502a

    Mar 19, 2009
    I have a 3.4 GHz 27-inch model and I do also notice the fans stay at a minimum 1200 RPM, which I can definitely hear when the room is quiet. I'm fully deaf in one ear so I think I can safely say if I can hear it, others can too. It's not obnoxious, and the iMac has full desktop components so I'd rather Apple keep them cool and regulate fan speed reasonably than turn it down to such an extent that shortens their life.

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