IMac – How to properly set SSD Fan Control on iMac late 2009 after SSD upgrade

hard driveimacssdtemperature

I’ve upgraded my late 2009 iMac 27” with an SSD hard drive.

Because of the fan noise, I’ve installed SSD Fan Control, but I’m not sure how to set it properly, avoiding to reach high internal temperature that could damage hardware.

Using “SMART” mode fan are very quiet; using “Auto” mode are more noisy.

For now my settings are the following:

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What does “1100 RPM @ 45 C” means? On the screenshot you can see that the temperature is 38°C, but the fan RPM is 1499…

Do you think these are good settings for me?

Thanks very much for the help

Francesco

Best Answer

The fan is running at 1499RPM at 38C, despite the settings of 1100RPM at 45C, because of a harmless bug in the SSD Fan Control app.

The bug is easy to reproduce:

  • Select Manual, and set the speed to 1500RPM
  • Select SMART, and the fan stays at 1499-1500 RPM

To "kick" the app back in to correct SMART operation:

  • Set the lower bound to a value below the ambient temperature (30C, for example), such that the fan speed increases
  • Set the lower bound back to 45C

Problem solved.

As for installing a temperature sensor, forget it. Francesco has a late 2009 model iMac 27" - these were not shipped with temperature sensors taped to the drive, rather with a proprietary cable connection direct to a special extra port on the drive.

The SSD Fan Control app works brilliantly on these old machines, once you understand the strange behaviour of this bug (and the workaround, described above).

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