5 Replies Latest reply: Jul 7, 2014 3:22 PM by Kappy
Pashty Level 1 Level 1 (0 points)

Hi,

 

I used to have a late 2006 iMac. It's fans never make a sound.

 

On my new (late 2013) 21.5 inch 2.7 GHz Intel Core i5 8GB RAM OSX 10.9.4 iMac the fans goes on every now and then. When this new iMac was 2 months old the fans were constantly on. I ran a self diagnostics test and the test showed there was a fan problem. I took it in for repair at the Apple store and they replaced the logic board.

 

Since then the fans make noise, but only for a few seconds every hour or so. I tried resetting the SMC by unplugging it for a minute, but nothing changed.

 

Is that normal?

 

By the way - the self diagnostics test now shows everything is OK.

 

Thanks!

 

Asaf

  • Kappy Level 10 Level 10 (250,120 points)

    It could be if the computer is getting hot from use. This will cause the fans to ramp up in order to cool it down. You may want to check for something running amok and causing the computer to heat up. I would also install a utility to monitor temps and fan speeds: iStat Menus 4.21.

     

    Pre-Mavericks

     

    Open Activity Monitor in the Utilities folder.  Select All Processes from the Processes dropdown menu.  Click twice on the CPU% column header to display in descending order.  If you find a process using a large amount of CPU time (>=70,) then select the process and click on the Quit icon in the toolbar.  Click on the Force Quit button to kill the process.  See if that helps.  Be sure to note the name of the runaway process so you can track down the cause of the problem.

     

    Mavericks and later

     

    Open Activity Monitor in the Utilities folder.  Select All Processes from the View menu.  Click on the CPU tab in the toolbar. Click twice on the CPU% column header to display in descending order.  If you find a process using a large amount of CPU time (>=70,) then select the process and click on the Quit icon in the toolbar.  Click on the Force Quit button to kill the process.  See if that helps.  Be sure to note the name of the runaway process so you can track down the cause of the problem.

  • Pashty Level 1 Level 1 (0 points)

    Thanks Kappy!

     

    Just downloaded the iStat Menus as you suggested. I'll look for something irregular on those sensors.

     

    Regarding the CPU, since I'm only using basic applications (Safari, Chrome, iPhone, iTunes, Mail...) almost the entire time the CPU is running at very low %.

     

    Thanks again!

     

    Asaf

  • Kappy Level 10 Level 10 (250,120 points)

    A word of advice: Get rid of Chrome. It's a known memory hog with fits of incompatibility. And, don't use two browsers at the same time. If you are going to use Safari, then quit Chrome and vice-versa. Or just don't use Chrome.

  • Pashty Level 1 Level 1 (0 points)

    OK,

     

    So I installed iStat Menus. What I can see is that when I hear the fan noise the fan speed goes up to 4000 RPM. When the noise stops the speed goes down to 1400 RPM.

     

    I can also see that there is no clear correlation between sensors temperature and fan speed. Meaning, when the fan goes from 1400 to 4000 RPM the sensors show the same (more or less) temperature.

     

    Most of the CPU is running at very low load (most of the time about 2% load). Again, no correlation between CPU load and fan noise / speed.

     

    One other thing I noticed is that sometime the fan noise appears when the computer is supposed to be sleeping.

     

    Is that normal iMac behavior?

  • Kappy Level 10 Level 10 (250,120 points)

    Try Intel-based Macs: Resetting the System Management Controller (SMC). If this isn't helpful, then: take the computer in for service, then, while it's in warranty. This is not proper behavior.