‘HDD Fan Control Preference Pane’
We have done lots of testing to find the best defaults to suit most drives and situations, and will continue to improve the defaults in updates if necessary. So for most users you should leave the defaults in place. We would only recommend changing settings if you have a drive for which they are not suitable, or you wish to have the fan running more, or less than the defaults provide.
The graph on the preference pane shows the fan speed to temperature relationship, temperature along the bottom axis, fan speed up the side. This shows the higher the temperature, the faster the fan. What you are generally trying to achieve is to reach the max fan speed of 6000rpm, about 5C below the max operating temperature for your drive. For when the fan starts to increase we would recommend setting this about 5-10C above normal idle HDD temperature.
This is the base speed for the HDD Fan. The fan has a hardware low limit of 1000rpm, and cannot go slower than this, for most users this should be the setting you use. You may want to increase this to provide extra constant cooling to your drive, but note this will increase the fan noise.
This is the HDD Temperature that the HDD Fan will start increasing its speed from, reaching maximum speed at value specified with “Temperature that Fan Speed is at maximum”.
This is the temperature that the fan will have reached its maximum speed of 6000rpm. Thus providing the maximum cooling it can, this should be below the maximum operating temperature for your drive.