After installing the SSD: the fan in the iMac runs continuously at full speed

SSD fan control
SSD fan control
With SSD Fan Control you can “calm down” your iMac again and get the fans quiet.

For some people, after upgrading their Apple iMacs with an SSD, the problem is that the fan revs up to full speed after a few minutes and is constantly ventilating at full speed - that is quite loud and sounds like a plane taking off. ;-) This occurs, among other things, if you remove the hard disk installed at the factory from the 2009, 2010 and 2011 iMacs and install an SSD with a [3,5 "to 2,5" hard disk adapter-> hard disk adapter]. The reason for the fan noise is probably due to a temperature sensor which is built into the hard disk and which is queried on the original hard disk via a special firmware and a special connector. Since the iMac does not receive this information about the temperature of the disk from the SSD, it accelerates to be on the safe side and lets the fan run full.

But there is a solution. And a free one at that! If you look at the App “SSD Fan Control” installed, the fan is regulated down and you get a quiet iMac again. The author of the software would be happy to receive a donation via Paypal, but he still offers the software free to download at. The software gives the user control over the fans and allows them to set their own speed.

SSD Fan Control settings

The author of the plugin gives a short guide on how to find the right settings:

  1. Download the software package
  2. Run the installer (Mac should restart afterwards)
  3. Start the “SSD Fan Control” program
  4. Then use the individual controls to find the fan that makes the noise
  5. Then regulate the loud fans down manually or via the “Smart” option. (Smart would be better, because then you can rule out that overheating can occur).
  6. Enjoy the “Sound of Silence” :)

Update 22.02.2016/XNUMX/XNUMX: Compatible with El Capitan + tips

Another note: the program is also compatible with OS X El Capitan. If you still have problems after updating to El Capitan, you can reinstall the SSD Fan Control software over it and it should work again.

Because of the settings: In the program there is an option “Smart”. If you choose this, the fan should become quiet and increase again at high temperatures. To be on the safe side, you can run something computationally intensive and then keep an eye on the temperatures of the individual sensors. They shouldn't be over 90-100 degrees for long. After that, the CPU usually clocks itself down ... you can tell that everything reacts very slowly and the mouse pointer is lame.

Question to readers: Mojave compatible?

A reader asked me whether SSD Fan Control is also compatible with the new macOS Mojave. Maybe someone already has it in operation and can leave a short feedback here as a comment. I would then note it in the article. According to the developer side, there is only one compatibility up to High Sierra. But there is also a tip if it should no longer work after a macOS upgrade:

SSD Fan Control is compatible with MacOS 10.13 (High Sierra). If it fails after upgrading MacOS, try an SMC reset first. In some cases reinstalling is required.

In other words: If the software no longer likes after the update, the best thing to do is to run one SMC reset off ... if it still refuses to work, reinstalling the fan control software could help.


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37 Responses to "After installing an SSD: The fan in the iMac runs at full speed all the time"

  1. Hi Joel,

    I think it's a great idea to make the fan controller available.
    For me, I cannot set the RPM for the SSD fan, ie I do NOT get the value below 1600 - it goes higher, but I cannot notice an audible effect (is probably because the fan is turning to maximum output anyway, right?)
    iMac early 2009 with Samsung SSD 850 EVO 500GB
    2.93GHz Intel Core 2 Duo
    8GB DDR3 memory
    S / N: W89152HD0TL

    An idea
    I would appreciate your feedback
    Thank you

  2. hello i got ssd from samsung built into my mac! I also downloaded the ssd fan controler app, but my question now is, how do I best set up the app so that no damage occurs?

  3. I have now solved this with the fan control. However, this “SMART” option does not exist for me. Not with the old version and not with the brand new one either. (v. 1.4.0)

    1. Hello Manuel! Is that no longer the case? I saw it at a friend who installed it. There was an option there. But maybe it's now "car" or something like that. Otherwise, I would adjust the fan speed so that it is not just annoying. And maybe keep an eye on the other temperature sensors in the Mac. The CPU should not get warmer than 80 degrees in the long term. My CPU goes up to 100 degrees under load for a few minutes, but that shouldn't be permanent. But maybe you still find “Smart”. :)

  4. Oliver Biegert


    great thing and thank you very much! One question: The program still seems to be running in the background when the computer is restarted. Is it possible to close or uninstall the program so that the old setting is running again?

    Danke & Gruß

    1. Hello Oli!

      It is definitely possible. It's just a program that doesn't change anything when you uninstall it. If the software itself does not offer an uninstall option, then software such as “AppCleaner” or “CleanMyMac” a good way to remove all “pieces” of a program. I hope this helps you!

  5. I have an iMac 2011 21.5. My son installed the Samsung SSD 850 evo 500GB in December 2015. Installed SSD Fan Control. Everything OK. Occasional crash. First thought it was on Fb because I play there. Since May crash more and more often. I let the controller run. As soon as the temperature reached 39-40 degrees at 1100Um the Mac crashed. I've been watching it for over 2 months. A hardware test showed all ok except for “4SNS/1/40000000:THOO-9.000”. I entered the code via google: Hard Drive Thermal Sensor/Temperature/Hard Disk Group. I set Fan Control to Auto today, the fan was significantly louder, but crashed after the game in Fb.. 17:15 p.m. to 2350/36 degrees/ 17:16 p.m. 2x off+on / 17:17 p.m. 2x off+on. RPM went down to 1100/37 degrees/ RPM up again. Wanted to write mail to my son, crash. Temperature at 3000/37.
    Speed ​​goes up and down, fan louder. I have now switched back to Smart. It works during normal operation, but the Mac turns off as soon as I play. My son also wants to do research. But thought I'll write to you. The comments I have found so far are all older.

    1. Hello Meggie! If I understand correctly, your Mac won't get too hot. Temperatures of 90-100 degrees Celsius would be too hot. This could lead to crashes, but actually the processor then also switches to an emergency mode and processes tasks more slowly so that it does not overheat. If your Mac crashes without it getting hot, it could also be due to defective memory. Or if it keeps coming back to Facebook games, then the browser could also have a problem. I would test whether it also crashes when you play the games with Chrome or Opera. LG! Jens

      1. SSD Control Hard Disk is again at 1100 and 30 degrees or 6300/70 degrees. On Monday 8.8. at 9:16 normal operation, checking mails etc. From 9:30 am on Fb via Safari (by the way, I always go to Fb) Bubble Witch until 9:41 am then 2x off / on display 1600/35. 9: 43h at 1880/36. Then I switched off the PC.
        In the evening at 22pm to 1am switched on and only normal operation mails and notebook search 1600/34. Nothing has happened. The fan is absolutely quiet, but it must run, otherwise it would not have turned up and down in AUTO mode. I ran the hardware test completely, it did not show any errors, except for the sensor / hard drive. This means that it shows an error that cannot be there, since the original hard drive is no longer there, but has been replaced. I also played Fb via Firefox once and it crashed too. We are already thinking about reinstalling the old hard drive.

        1. Hello Meggie!

          If the system is still on the old hard drive, install it and see if everything works without a crash. If so, then I would complain about the hard drive. Best wishes!


          1. Hello Jens, thank you first.
            Have PC on since 18: 08h (1100/26). At 19h Safari Fb (1500/33) Bubble Witch played through and at 19:33 Candy Crash - 19:25 crash at 200/37. 2x off / on then up to 2140 and 38. RPM now goes down to 1700/35 with no operation. Will make the suggestion to my son.

          2. Hello Jens, have another question. I got Mavericks on it with Kaul Lion.
            Since November 15 El Capitan. The SSD was only installed in mid-December. The crashes came after that. Not often, but more and more since June. But I assume that El Capitan runs the same under SSD.

          3. Right... for the OS it's just a "normal" hard drive... so there's no difference that should/could cause the crashes. However, if the hard drive itself has a defective controller or something else doesn't work, crashes can occur. For this reason, it is always important to find out which part of the Mac is causing the problems. You can also start with an external hard drive and then do your everyday stuff. If there is no crash then, I would bet on the internal SSD. It could also be loose cables. I had that once with an old G5 Mac. It worked for 2 weeks and then the hard drive cable was loose and the crashes started. Man, it took me a long time to locate the error. :D

  6. Hello!

    I also got the iMac (27 inch, end of 2009) and a new Samsung SSD 850 EVO with 1TB installed.
    Really had the effect of a jet taking off ;-)
    After installing the Fan Control, the PC started to land again ...
    The “Smart” button is still there in the bottom left of the footer. I just hope that the computer isn't going to be used for heating

    1. Hello Heiko! I am pleased that your Mac no longer simulates the approach path from Frankfurt. : D I think you can also see the temperatures of the various sensors in the SSD Fan Control. They shouldn't be permanently above 80-90 degrees. If they are under, everything is ok. But the processor also has overheating protection that prevents it from getting too hot.

  7. Hi all,
    Yesterday I bought a used iMac (SSD 500GB and 16GB RAM) and I was really looking forward to this device. The disappointment was all the greater when it sounded like an airplane immediately after switching it on (as already described by others).
    Will test the software mentioned here and report. Please keep your fingers crossed for me;)

  8. \ O / with just one click (if you disregard the installation?) Significantly quieter!
    “Smart” is present on my version.

  9. Have run the program successfully for several months in an IMac converted with an SSD. The computer has not been on for a week and since then the Ventis have been running at full speed and I can't get to the value of the optical drive. No matter manual / auto mode, it does not show any temperature and does not change anything when the revolutions are changed. I reinstalled everything again, unfortunately always the same result. Anyone have an idea? Thanks…

    1. Hello Olaf! Unfortunately, I don't know of a solution now. Maybe there is a reader who already had something like that? I hope someone has a tip. Otherwise it would be very annoying to work with the fan ... :)

  10. Hello!
    I swapped an Imac Early 2009 and my hard drive. Then the CPU fan runs at full speed. Can you also regulate the CPU fan?

    1. Hello Roman! You'd have to try that out in the app. Unfortunately I don't know because I haven't installed the app. But the question is whether you really want to turn the CPU cooler down. If the CPU gets permanently too hot (> 90 degrees), then it breaks. LG! Jens

  11. Hello Jens, now I have to ask / write something. My friend recently got a Samsung EVO 2007 SSD in her old iMac in mid-860. El Capitan was installed. Jet plane noise. SSD Fan Control loaded. The program shows the temperature, but you cannot regulate the fans with the buttons, no reaction. Switching from Auto to Smart or even to Manual does nothing at all. SMC reset. Same symptoms. Perhaps you have an idea or of course a reader would like, that would be great ?! LG

    1. Hello Lea! What temperature does the program show you? Anything beyond 70-80 ° C? Otherwise I would not understand why it ventilates so maximally. Maybe something went wrong when installing the SSD and the sensor is not sending correct values ​​to the Mac? Then of course he can ventilate a wolf and it doesn't get any cooler according to the sensor ...

      1. Hello Jens, the program actually displays normal values, around 40 C°. When controlling the temperature using the manual button, the "desired" values ​​are displayed, but the fans actually roar at full power no matter what you set. What could have gone wrong with the Einbach? An acquaintance of hers did it, but he didn't know what to do either...

        Now we've tried the Macs Fan Control app. Same game. It works on my old iMac, and the fans are still running at full speed on my old iMac. Today came a virus message that you couldn't do anything with, maybe from this program? It's getting stupid. :( Do you have any other ideas?

        1. It's strange. I can only explain it to myself that the Mac gets virtually no response from the sensor and, to be on the safe side, switches the fan to maximum so that there is no damage. You probably have to look again in your Mac to see if there is a loose cable or something like that. You won't be able to solve this with the software. But I would be happy if you could keep us up to date on how it goes!

  12. Hi Jens,
    I also gave my iMac (late 2009) a new SSD and the noise was “scary” ;) Now I downloaded the app and I hear… NOTHING! sound of silence Thanks for this tip. I thought I did something wrong ;(

    1000 thanks and best regards

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