2 Replies Latest reply: Jan 17, 2009 4:10 AM by DaddyPaycheck
Cibby Level 1 Level 1 (30 points)
Can someone either post a reply or a link to a previous thread on how to test if my iMac fans are working properly? I have the original 20" model.

I get a whirring sound most of the time, and then others the fan just blasts even with nothing major running. I thought it was just a 10.5 issue, but now I'm wondering if it could be a faulty fan. If you can tell me how to check that would be great, thanks!

15 MBP Santa Rosa, 20 iMac G5, Mac OS X (10.5.5)
  • steve626 Level 4 Level 4 (1,460 points)
    You can get a program called XResourceGraph (free) at

    http://www.gauchosoft.com/Software/X%20Resource%20Graph/General%20Info/

    It shows temperatures at various locations inside your Mac. I installed it on our G5 iMac. It also shows how fast the fans are spinning (rpm). You can watch the temperature start to rise for the hard drive, or the processor etc. and also simultaneously, you will see the appropriate fan increase in rpm and then the temperature stabilizes or comes back down. Mine stays between 130 and 150 degrees F for the processor. If one of your fans shows as 0 rpm, you will know it is broken. My fans run between 1500 and 2000 rpm mostly, but when doing a lot of stuff, I have seen them up to 4000 rpm, while the temperature stays constant (presumably because of the fans).

    I think these fans and the need to actively cool the iMac G5 is a weakness in the design, although it's a great computer. In contrast, the much cooler Intel chip in the new iMacs has very little need for such active cooling. I can't hear ANY fan hum at all in my daughter's new iMac.

    This would be important to get fixed if it is the case because the G5 PPC chip throws off a lot of heat and your computer is likely to overheat sooner rather than later if one or the fans has stopped.
  • DaddyPaycheck Level 6 Level 6 (16,035 points)
    If the fans were not working properly the iMac would overheat and shut itself down.

    -DP