How to properly set SSD Fan Control on iMac late 2009 after SSD upgrade
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:
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
Solution 1:
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).
Solution 2:
This is one of those scenarios that leave me scratching my head because it's solution to a symptom without a basic understanding the of the problem (aka an XY Problem)
"1100 RPM and 45C" means:
The fan is spinning at 1,100 Revolutions Per Minute (RPM)
45C is the temperature in Celsius (45 degrees Celsius or 113 in Fahrenheit)
Your fans spin up for one single reason only, the temp readings has indicated the the temperature is a certain level and needs to cool things down. What you have essentially done here with SMCFanControl is to override the system's ability to properly cool your iMac.
So, to properly control the fan in your iMac, you need to address the problem:
The issue, most likely, is that after your upgrade of the SSD, you didn't account for the in-line temperature sensor which sends the correct data back to the fan controller.