When I first got my new iMac in late 2010, I was surprised at how hot the aluminum body got during CPU and GPU intensive tasks. This was of concern to me, as I was unsure whether or not the fans were operating properly. On a Windows machine, fan control programs are all over the place, and many systems come with this kind of software already installed. Like many geeks out there, I have come to appreciate the benefits of proactive cooling. A cooler system lasts longer than one that frequently overheats. This is where Fan Control 1.2 by Lobotomo comes in.
I was surprised to find out that this app, designed primarily for use in MacBook Pros (noted for having cooling issues) worked great on an iMac. In fact, the app recognized the iMac right away and took control of the fans without any hiccups.
Fan Control 1.2 works as an addition to your System Preference panel and allows you to set the lower and upper temperature thresholds, slowest fan speeds (for individual fans), and monitor temperatures and fan speeds in a variety of ways. You could take the proactive approach and up the fan speed at lower temperatures or keep things as they are. Setting the temperature thresholds allows you to control the points at which the automatic fan control systems kick in. For the sake of safety, Fan Control keeps the built-in automatic control system from OS X intact.
This is a great way to check your system’s fan health at a glance. If the desired speed varies too much from the current speed, this can be a clear indication that something is wrong and you may have a fan on its way out. If you use Fan Control with an iMac, it displays the CPU, HD, and DVD fans. Should you install it on a MacBook Pro, the right and left fans are displayed accordingly.
Overall, this is the best solution I’ve found to keep my iMac cool, even during intense video rendering and gaming. Fan Control is open source and is distributed under the GNU General Public License (GPL). After using this app every minute of every day since the beginning of the year, I have yet to experience any trouble or instability.