iMac retina 4000rpm loud fan when idle and under 30°

Discussion in 'iMac' started by zixuTech, Sep 7, 2015.

  1. zixuTech macrumors newbie


    Sep 7, 2015
    Hello guys.
    There are thousands of threads about loud fans and I read most of them, still couldn't find a solution to lower my iMac retina 2013 model's fan speed.

    Suddenly couple weeks ago it decided to start blowing the hell out of the fan. Making me nervous and impossible to stand even next to it. When i say loud - it is so loud that I cannot even hear my own toughs.

    I tried to do SMC/NVRAM reset, still same loudness.

    Installed\removed bunch of "fan control" software, they detect that fan is on 4k rpm speed but refuses to lower it down or control it.

    I measured the temperature with them softwares and tech tool pro. And all shows them within a range and under 30°C.

    When I boot with other OS on usb hdd it still crazy loud.
    Even in recovery mode it is loud.

    I read and read and seems like all of the solutions around just are not applicable on this machine.

    Took it to authorised repair shop twice and they said they couldn't "replicate" the problem. But when I use it for a while it gets loud again, then if I turn it off overnight and try to use it next day. It wokes up like a monster with it loudness and never comes down.

    I noticed even if I press sleep from the menu. It turns off the screen but I still can hear the fan. If I decide to wake it, monitor turns on so quick like it never gone to sleep mode and just turned off the monitor.

    Only way how I can calm it down is by shutting it down.

    Guys help please. Can't find a solution for it. And it looks like can't get that solution in authorised repair centres neither.

    It comes with I series intel cpu, dedicated nvidia graphic and 2.5" hard drive.

    Thanks in advance.
  2. hobowankenobi, Sep 14, 2015
    Last edited: Sep 14, 2015

    hobowankenobi macrumors 6502a

    Aug 27, 2015
    on the land line mr. smith.
    It is likely one of 3 things:

    1. Possible that it could be OS.

    2. Bad sensor on HD. Apple started using HDs with a special firmware about 2009 IFRC that would supply heat sensor info to regulate HD via fan speed.

    3. There are several other sensors (varies a bit by model), any of which could possibly be supplying erroneous temp readings causing the fan(s) to ramp up.

    For #1: nice to boot to a fresh, clean OS install. Could be from an external drive. If it behaves the same, likely not software. [sounds like this is already ruled out]

    For #2: Did you have the HD replaced or worked on? Any other reason to suspect the HD might trigger high temp readings?

    For #3: This the shop should catch. Again, varied a bit by model. Hard though. Apple has long history of having the fix being swapping out parts, like logic boards, which is expensive.

    If it were me, I would run Macs Fan Control, and watch the sensors and fan speeds to see if there is any heat issue, and hopefully figure out which sensor is triggering which fan. You say 30 degrees......but there are probably about 4 sensors/areas in your iMac.

    You said you ran several fan software tools. Any insight from them as to the different sensor readings?
  3. hobowankenobi macrumors 6502a

    Aug 27, 2015
    on the land line mr. smith.
    Oh, and having to shut it down in normal to get fans to shut down. Takes resetting the SMC controller, and sleep or reboot won't do it.
  4. zixuTech thread starter macrumors newbie


    Sep 7, 2015
    Hello hobowankenobi

    Thank you for your reply, yes it's well known with iMac and their fan issues. What I striked out from the faults is as follows:

    It couldn't possibly be OS issue, as I booted with external HDD and 10.9 / 10.10 and fan was loud as it is. Even same with recovery mode, which is odd.

    I believe after 2009 as you mentioned temperature information with bunch other info is collected straight via SMART data stored on HDD's firmware. It can be malfunctioning hard drive. However HDD diagnostic tools such as TechTool Pro can detect this SMART errors and report them. When I ran it, it reported everything is alright. Present hard drive in this iMac is Apple Seagate 1TB hard drive and I believe it is the original shipped drive.
    It was purchased through a retailer less than 2years ago, and I am not sure if it is the original or apple replacement hard drive inside. Unfortunately it is slim model and it is pain to be taken apart without risk of damaging front screen.

    For the several other sensors you mentioned, only way of catching their issues would be to run apple service diagnostic tests, but as you are aware this model comes with no optical drive. is it any way you can point me where I can prepare USB Diagnostic tools for this model.

    My info is bit outdated for this models, I miss dealing with pre-2009 models, there were physical thermal sensors attached to the harddrive, heatsinks, motherboard. Now with everything integrated within devices makes it harder when it comes to repairs. Old technology rocks.

    About Fan control software, I've tried following ones with no success on iMac Retina 2013:

    SMC/Pram Reset - I applied both procedures which I am well aware of with previous models, didn't even slightly reduce fan noise. Looks like there may be some hardware fault, which may would push me to a gap if I start swapping parts.

    hobowankenobi I appreciate your reply, please do let me know if you come across any fan control software wich actually controls 2013 iMac Retina fans. So I can exclude sensor fault possibility.

    Thank you guys, great community is gathered here.
  5. hobowankenobi macrumors 6502a

    Aug 27, 2015
    on the land line mr. smith.
    Well, kudos to you for all the work.

    Too bad my weapon of choice was no help. Though they say all models, I wonder if there is/will be an update that may help with new(er) machines. I assume you have tried the latest version. No way to know if/when an update might help

    I am out of the loop on the latest iMacs too, will dig around and see what I can find. Oh, and is your model new enough to run the Apple Hardware Test? Might help diagnose, if not fix.

    And to be clear.....when running some of the better fan/temp software, did you see any temps that could be an issue? It is possible the fans are controlling a real heat issue? Dust...or something else?
  6. steve23094 macrumors 68020


    Apr 23, 2013
    I was going to say to take it into Apple and get it looked at under warranty. This is because I read 'iMac Retina' in your thread title and message text, and all of those will still all be under warranty (it was released in October 2014). But then I continued to read that you have a 2013 model.

    Just for clarification. Your 2013 iMac is not what is known as a Retina iMac.
  7. zixuTech thread starter macrumors newbie


    Sep 7, 2015
    It's outside of warranty steve, that's why I said it's 2013 and yes it's is retina, as it has retina screen.
    One more unsolved mystery for me. o_O
  8. Serban Suspended

    Jan 8, 2013
  9. imanidiot Suspended

    May 1, 2011
    Denver, CO
    If it's a 2013 model, and an iMac, it is not Retina.

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