This iMac: http://www.everymac.com/systems/apple/imac/stats/imac-core-2-duo-2.16-20-inch-specs.html The problem: My late-2006 iMac has had an issue where the system freezes up for awhile, which I thought was due to overheating and a bad cpu temp sensor. I installed the fan control prefpane and cranked the base fan speeds way up (to about 2000rpm) which helped significantly but not completely. This morning, I boot up the computer and the fans are going like gangbusters. As you can see in the attached screenshot however, the system is not aware of any fans or temp sensors at all. Fans all read (-1) and temp sensors all read 32°F/0°C, which is the null value for this model. The questions: Any way this is not a hardware problem? Can these sensors be replaced? How hard is it? Is this going to progress to the point where actual damage is done to the CPU/GPU/etc.? Any help on this would be appreciated, thanks!