Phantasmic is a system menubar application that monitors the temperature sensors of your Macintosh computer and optionally allows you to control the system fan(s).
There is no icon in the Dock, but instead a menu is added to the system menubar displaying a temperature and fan speed.
If you click on this menu you will see a number of commands allowing you to view more detailed information.
On the first run you will be prompted for your system administrator credentials. Phantasmic requires a small privileged helper program to make adjustments to the hardware settings.
By default, Phantasmic operates in a monitor mode and makes no adjustments to your system fans, simply reporting the readings from the various sensors built into your Macintosh hardware.
Fan adjustment is enabled by checking the 'Modify Fan' checkbox.
When controlling the fans you can choose either set the fan to constant speed or alternatively allow variable speed, tracking a selected temperature sensor between an upper and lower value.
If you choose to use variable speed then you must also use one of the other three methods to track the temperature. Each method will realize the same fan speeds at the temperature endpoints but will have slightly different tracking characteristics between the two settings. In all cases, the fan will not go faster than the maximum value or slower than the minimum value (except for some minor overshoot in either direction).
Updated on Feb 22 2022