Home > Mac, Tech Tips, Technology > Solution to the noisy fans on a Core 2 Duo Intel Mac Mini

Solution to the noisy fans on a Core 2 Duo Intel Mac Mini


As those who’ve been reading my blog may know, I started my conversion to the other side (Mac) on the 28th of Feb, 2005 with the purchase of a 1.42 GHz Mac Mini after gushing over my now wife’s 12″ Power Book.

I was taken by its size, it’s sleek lines, OS X and last but not least, its comparative silence next to my air moving PC.

I kept this machine for 3 years before handing it over to my brother in a vain attempt at getting him to move into the digital world (he is an artist of insane calibre, but with zero digital knowhow).

To replace it, I bought an Intel Mac Mini when the Core 2 Duo models were released.

Since then, I’ve been enjoying trouble free compting, but have had only one issue with my machine.

It’s an issue that started the moment I upgraded the RAM from its inital 1Gb to 2Gb and Continued after a further upgrade to 3 and then 4Gb.

That issue is a fan that revs up as soon as the system comes under even minor stress, drowning out the sound of my beige box Windows 3GHz P4 system with 4 hard disks!

I’m not talking about a fan that revs up and gets loud shortly after booting and stays loud constantly, I’m talking about a fan that revs up as soon as the system shows even a modicum of activity.

With the supplied 1Gb stick of RAM, this issue did not occur, but add a second stick and the fan goes berserk at any opportunity. The fan revs up so much that the CPU, GPU and HDD actually cool down below their respective idling temperatures!

Anyway, there is a Really Simple Solution (TM).

Step 1: Download and install SMC Fan Control.

Step 2: Open a terminal window

Step 3: type the following:

/Applications/smcFanControl.app/Contents/Resources/smc -k F0Mx -w 3e80

And your fan will become a much more sedate affair.

Why? Because this limits your fan to about 4000 RPM rather than the ear numbing 5500 RPM it is usually capable of.

A 20% or so reduction doesn’t sound much, but remember that fan noise often has sometimes a squared or cubed relation to rotational speed, and that ignores a system working at its mechanical limits, so even a minor reduction can give big gains!

Try it and see.

For the curious, the 4 digit number after the -w is:

HEX (Base 16) : Fan Speed x 4

If you set the speed too low, I recommend installing ANOTHER FAVE OF MINE, Temperature Monitor to keep an eye on your newly silenced computer, especially in summer.

  1. June 18, 2009 at 6:12 pm


    Thanks a lot for this! I have to try this at home tonight!! Can’t wait, that fan noise is driving me crazy …

    What’s the meximum temperature that the mac mini should experience??

    Have a nice day!

    • nanchatte
      June 18, 2009 at 6:34 pm

      It’s a nice fix…

      I’m using Lingon to run the script every 5 minutes so that it kicks in after wake ups… (Wakeups reset the fan behaviour, it seems).

      I’ve noticed the CPU reach stable temps of 63C once or twice after reducing the fan speed (previous maxes were about 58C).. and the hard disk no longer gets supercooled back down to room temp when the fan is working full blast. instead it hovers at around 40C under load, which is quite respectable.

      Use Hardware Monitor or its freebie cousin temperature Monitor to keep a track on the temps of everything with a history graph.

  2. June 19, 2009 at 12:55 am

    Thanks, this works great!

    My mac mini core 2 duo still makes too much noise for my gusto though 😉

    Is it possible to lower the fans to even more than just 4000rpm? Let’s say 3500 or 3000rpm? What would the HEX number be??


    • nanchatte
      June 19, 2009 at 2:13 pm

      Hi there Grommel.

      The formula is simple… its 4 x frequency (in decimal) and then converted to hex.

      Just use the calculator program,
      make sure its in decimal – normal – mode.
      type in the speed you want, (let’s say 3000)
      then multiply it by 4 (12000)
      Now press CMD-3 to set it to programmer mode.
      And check that the HEX button (to the right, below the LCD) is pressed.
      You should see 0x2EE0.
      Just use the last 4 digits (2EE0).

      Please make sure you’re monitoring your temps and fan speeds with hardware monitor, iStat or another proggy. I’m not responsible if your computer melts when you accidentally set your fan speed to 17 RPM!

      p.s. the fan doeasn’t seem to operate reliably below about 1000 RPM. Be warned.

      p.p.s. If your computer is still under Apple Care or warranty, have the fan replaced. The newer fans are quieter (so it would seem according to some). Say that the fan makes intermittent strange buzzing sounds once every couple of weeks or so, goes silent, heats up, smells a bit funny (important this one) and then switches off without notice.

      Of course, remove all traces of SMC or they’ll blame you for the trouble.

      I was too busy to take mine in to the shop and couldn’t be arsed with the 10 day turnaround time they said it might take.

  3. June 19, 2009 at 3:18 pm

    Thanks a lot! And don’t worry, I have an eye on the temperature!! 🙂

    What’s the max temperature that’s ok?

    I’m thinking about exchanging the fan but just like you it annoys me to go there and to not have my mac for a couple of days! 😉

    I’ll see …

    • nanchatte
      June 20, 2009 at 11:00 pm

      Sorry mate, can’t help with a max temp… I do know that most CPU will run for years at 80C though, take the hot running iMac G5 for example. The CPU has an auto shutdown set at at least 85C.

      Mine’s run comfortably for years at 60+ and much of the time over 70 due to the defective iMac cooling. Even when the rest of the computer had to be replaced twice in the meantime, the CPU itself was fine on each occasion!

      HDDs should be kept at less than 50 though, even under heavy stress, so make sure u keep an eye on the disk, too.

  4. Catmandoes
    October 13, 2009 at 2:38 am

    Great tip, worked well for me. Thanks very much

  5. Joe
    October 16, 2009 at 2:43 pm

    Is there a way to save the setting or make it permanent? I put my mini to sleep and when I started it back up I had to re-input the setting to reduce the fan speed.

  6. Lungo
    March 15, 2010 at 2:32 am

    Thanks for the hint

  7. wiredkiwi
    June 28, 2010 at 8:31 am

    Horray! It worked perfectly … thanks so much for your timely tip. Please tell me though, where did you come across the command line syntax for this app?

  8. John
    January 13, 2011 at 5:20 am

    Sometimes once people have installed new memory, they forget to plug the fan back onto the motherboard. The result is that the fan runs at full speed unless a 3rd party software (as you mention here) is used to slow it down.

    Always worth double-checking the two black wires are plugged into the motherboard. Also make sure one hasn’t performed a PMU on an Intel mac mini – this will screw things up and the fan will always be loud…

    • nanchatte
      February 10, 2011 at 6:43 pm

      THis might be the case if the fans are on full, but the fans respond to CPU/GPU activity/load, so I don’t believe that this is the problem.
      I have used SMC Fan Control successfully to mitigate the noise issue.

  9. April 25, 2011 at 3:22 am


    I hope someone is still monitoring this particular topic.

    I have a 2.66 GHz Intel Core 2 Duo, 4 GB 1067 MHz DDR3 Mini-Mac 4.1 running 10.6.7, SMC Version (system): 1.65f2v.

    I’ve had it for several months and I recently noticed that the fan was making a lot of noise, even when it was sleeping. It does cut off occasionally. I installed the SMC Fan Control APP and then noticed this post. I tried using the terminal and cut and pasted your line of modification to lower the fan speed but SMCFC still shows 5504 RPM at 90 Degrees F/31 Degrees C. So, it’s not even hot.

    Are you able to tell me what I might be doing wrong or does the new operating system require a different wording for the modification via the terminal?

    Thank in advance.

    • nanchatte
      May 1, 2011 at 3:58 am

      Did you get any errors when you ran that command?
      Did you install SMC fan control into the Applications folder or are you running it from it’s DMG file?

      Have you ever opened your computer?
      Have you increased the RAM or changed HDD?

      Also, have you tried typing
      sudo -s
      and entering your password before running the command?
      It can take a few minutes for the setting to take effect.

  10. May 2, 2011 at 2:05 am

    Thanks for the post Nanchatte.

    Turns out that I neglected to ENTER after pasting the command. It works fine.

    I have to enter it every time the puter wakes up or I reboot. That’s a minor annoyance but I hope to arrange an appointment with Apple in Norfolk. Only a couple of weeks after I got the Mini-Mac the hard drive bit the dust and had to be replaced. They may not have plugged everything in properly.

    • nanchatte
      May 4, 2011 at 12:59 am

      why don’t you use Lingon? It can auto run a command every 5 minutes or on boot, etc.

  11. May 4, 2011 at 3:17 am

    Lingon? Probably because I never heard of it. However, that’s still just a temporary fix but better than being annoyed. 🙂 I’ll research it.

  12. November 23, 2011 at 3:27 am

    Thank you very much!!


  13. G
    December 15, 2011 at 6:20 am

    Thanks a lot. You make me happy.
    Just for curisity: To come back to original setting of the fan?

  14. RJ
    December 29, 2011 at 9:46 am

    SMC installed with /Applications/smcFanControl.app/Contents/Resources/smc -k F0Mx -w 3e80
    entered in the Terminal just fixed my- all of a sudden, won’t go away no matter what i do, and i tried hard, loud fan on a late 2010 Mac Mini,2.53,4g. Fan speed dropped from 5400+ to 4k. Much better. Thanks
    PS. This problem occurs without load, cpu temp sensor or something must no longer be working.

  15. September 29, 2012 at 3:42 am

    thank you very much .. solved my problem with Mac Mini mid 2010 fan speed noise..
    but every time i log out or restart it will be back to 5000+ ,, so i had to use apple script editor to maks it automatic

    tell application “Terminal”
    do script “/Applications/smcFanControl.app/Contents/Resources/smc -k F0Mx -w 3e80”

    end tell

    quit application “Terminal”

  16. dyLAN
    May 4, 2013 at 1:51 am

    Thank you so much nanchatte! I’m relishing the 3500rpm ‘silence’ now after months of whirring madness

  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: