I have an early 2009 iMac. I got it pretty soon after it was released (about a year ago). It was always very silent and had to put my ear to the back to hear the fan. About a week ago the fan kicked on and now is always on regardless of what the computer is doing. I can have 8 apps open or none. If I shut down the computer, the fan turns off but kicks back on during startup. The iStat stats says the Hard Drive is at 1600rpm and the CPU fan is at 1200rpm. I don't know what these numbers used to be when it was quiet. Those numbers don't look very high to me as my MBA exhaust is currently at 2500rpm and I can't hear anything from it. The iMac though is incredibly annoying. Does anybody know what could be going on or do I need to take a trip to the Apple Store? Thank you.