iMac HDD Fan Control

If you have replaced your iMac’s Hard Drive with a new HDD or a SSD and the fan has started running at full speed creating a lot of noise, HDD Fan Control will control the fan speed in relation to the drives temperature, preventing the loud noise whilst keeping your drive safe from overheating a failure.

iMac HDD Fan Control does not require Apple’s temperature sensor or cable to obtain the drives temperature as it uses the S.M.A.R.T (Self-Monitoring, Analysis and Reporting Technology) protocol built into all drives, this means you no longer need the temperature sensor or cable for the fan to operate correctly.

Simply download, install, and enjoy the peace and quiet of your iMac again.



  • - Controls the Hard Drive Fan Speed Directly.
  • - Sets fan speed in relation to Hard Drives Temperature.
  • - Obtains Hard Drives Temperature using the S.M.A.R.T Interface so no need for the missing Apple temperature sensor, or cable.
  • - Runs at startup, so will work even when user is not logged in.
  • - Has fail safe feature to allow fan to go to full speed should it not be able to obtain temperature readings to protect the drive.
  • - Can be used with all SSD’s.
  • - Can be used with SSD’s and Hard Drives that do not provide temperature values by using the iMac’s internal temperature.
  • - Preference Pane allows user to set desired temp/speed relationship for their specific drive and or requirements.
  • - Small footprint, uses very little resources and is conservative with S.M.A.R.T interface use.



  • - Ability to use iMac’s internal temperature instead of S.M.A.R.T temperature for SSD drives that do not provide correct temperature data.
  • - Improved default settings.



  • - Automatic Updates.
  • - 1 Hour Demo mode.
  • - Improvements in some SSD Temperature data handling.



  • - Completely redesigned and improved UI.
  • - HDD Fan Control Monitor – Status Bar application allowing you to see HDD Temperature as reported by S.M.A.R.T and current fan speed, quick access to HDD Fan Control Preference Pane. (NOTE: Monitor not required for HDD Fan Control to run)
  • - Advanced features for systems with multiple SSD’s or HDD’s especially in 2011 iMac’s.
  • - Completely rewritten code with improved fan control algorithm and temperature response; optimized to access the drive’s S.M.A.R.T interface only when needed.
  • - Full override mode for SSD’s that do not report temperature or is reported incorrectly and drives that refuse to behave.
  • - Ability to select which drive to read SMART data from in multiple drive systems.
  • - Ability to reset settings to good default values.
  • - Mac OSX Lion Compatibility.


HDD Fan Control installs as a preference pane to allow you to control the speed of the internal hard drive fan and to set a temperature to speed relationship, temperature of the drive is obtained using S.M.A.R.T so an apple temperature sensor is not required.

With Version 2.0 you also get HDD Fan Control Monitor a small Status Bar App that displays your HDD temperature and the HDD Fans Speed, the menu allows you to set the Monitor to run at login (not required for HDD Fan Control to run) and a quick link to the Preference Pane.



Its primary use is to address the iMac hard drive fan issue, that causes the fan to run at full speed constantly making a lot of noise.

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iMac Hard Drive Replacement Fan Noise Issue

Since the late 2009 iMacs came out, replacing the hard drive has caused the internal Hard Drive Fan to start running at around 6000RPM.  This is due to Apple replacing the external Hard Drive temperature sensor with a proprietary firmware and using the drives internal sensor, replacement drives do not contain the firmware to deliver temperature data on the temperature sensor cable, when the iMac does not receive a good signal from the hard drive it puts the fan at full speed to protect the drive.

If you replace your drive your iMac will initially seem fine, but soon the fan will begin to speed up to full speed. Resetting the SMC (System Management Controller) will have a temporary effect, but again the fan will speed up.

Fixes people have used in the past included:

  • - Using smcFanControl and the terminal to set a MAX speed for the fan and writing scripts to start this after every sleep/restart.
  • - Shorting the temperature sensor cable (Not a possibility on 2011 iMacs) this tricks the iMac into thinking the drives temperature is very low, hence slow fan speed.

Both these fixes are less then perfect and leave the drive in a dangerous situation with no protection from overheating.

Another option people try is other Fan Control software, these programs will not work for this particular issue as they often only control the base speed, and if they do control the fans actual speed they rely on the temperature reported by the sensor which is now incorrect.

HDD Fan Control

HDD Fan Control works to fix this issue by reading the drives internal temperature using the S.M.A.R.T protocol and set the fans actual speed to a value good to protect the drive. It runs at startup and continually to always control the fan correctly, prevent the loud fan noise and protect the drive from overheating.


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You are a life saver!!! It works great, and I no longer have to hear the fan. Many thanks for your hard work on this!

Thanks for an awesome program. You have calmed my HDD wows.

software works perfectly! Great relief from that fan noise.

thank you for the quick fix, it works.

OMG, I totally did not believe this was going to work. I took in my computer for a new hard drive and I as soon as I got it home the fan went crazy. I knew I wouldn’t be able to continue to work that way. Within seconds of installing this program the fan instantly went off. My sanity is restored! Thanks!

thanks for the Fan Control software. The fan noise was freaking annoying after I replaced my 1TB HDD with a 2TB HDD.. even though I replaced the HDD with the same brand (Seagate) that utilized the same temperature plug. I even went back into the computer twice to double check all connections. Your codes saved me from reinstalling my old 1TB HDD.

Thank you so much for this software, it does EXACTLY what I need and saves me having to buy and install a temperature sensor to stick to the HDD (or jumper the existing sensor cable to disable monitoring of the HDDtemp)!


your software saved me from any of the other nasty solutions

Its great software and saved me a whole heap by enabling me to change out my HDD on my own, and not spend a lot of money. Apple already has way too much of my money already!!

HDD Fan Control works like a charm

Can’t even tell you how much I appreciate your work. My wife was close to tossing the iMac out the window to get rid of the noise. I replaced a failed drive out of warranty with the same model (but no apple firmware) months ago. Wasn’t comfortable with the short solution, and Apple “genius” support told me I needed to buy an “apple” drive. Thanks again.

I just wanted to drop you a quick line to say thanks for providing this excellent software at a very reasonable price…  Unfortunately, I’ve found it about 3 weeks too late — just replaced my HDD and had to buy a new sensor cable, as I accidentally removed some of the insulation on the wire…  This $10 app would have been a much quicker, and cheaper, fix than ordering a whole new cable and dealing with 6500RPM for 2 weeks =)

We used this software to control the fan. By default, HDD Fan Control sets the speed of the fan to 1000 rpm, which is much quieter than the 6000 rpm that the fan spins at without the utility.

To get the iMac working so I could observe the fan, I used HandBrake to convert a DVD file that was ripped to the hard drive. HDD Fan Control sped up the fan to keep the temperature down.

Finally, I found HDD Fan Control by Ben Surtees. Installed it and instantly, the HDD fan went back down to 1600 rpm and the iMac was silent again. What a relief!

HDD Fan Control rocks, saved my sanity after replacing a failed 1TB Seagate drive in my 2009 iMac. Thanks!

Thanks guys for a great app that solve one of the most irritating issues with Apples policies. All I need to know now is how do I claim the cost back from Apple?
Keep up the good work.

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I replaced my Hard Drive in my iMac and I now have a loud noise like a fan, will HDD Fan Control Help

This is exactly what HDD Fan Control was created for, that noise is the HDD Fan turning at 6000rpm, is does this as it cannot determine your HDD Temperature.

HDD Fan Control will read the drives temperature and set the fan to an appropriate speed, and the noise will stop.


I have replaced my Hard Drive and after some time the Fan gets louder, but resetting fixes it for a while, do I need HDD Fan Control?

Yes, this is typical of the temperature sensor issue.


What temperature settings should I use?

The default settings are OK for most drives, but we would suggest checking your drive temperature range and setting the temperatures so that the fan would be spinning at 6000rpm before the drives max operating temperature.


Does this work with all SSD’s even those that do not provide temperature data over S.M.A.R.T?

Yes it does, HDD Fan Control will use the iMac’s calculated internal temperature to keep your drive cool and the fan quiet.


Does this work with all HDD’s?

Yes it does.


Does this fix the hardware test failure?

Unfortunately no it does not, the iMac still cannot read temperature signals from its temperature sensor so will still report this during the test.


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All the latest news related to HDD Fan Control and the iMac Hard Drive Replacement Fan Issue.

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