This app is specifically designed just for such scenarios and it is aptly named Macs Fan Control. Those running a Windows operating system on a Mac might find that checking their system temperature can be a bit tricky, this is because the Mac has a few exclusive peculiarities. This is where DrFan comes in and solves all the headaches. Mac users know that fan control is poorly implemented on Mac OS, the OS likes to underclock the system CPU and GPU instead of boosting the fan speeds to drop the temperature. DrFan is a superb free (donationware) fan control software for iMacs which lets the user to better control the system fans.