iMac Fans ALWAYS ON and CPU 90-100%!?!

Discussion in 'iMac' started by Blazer5913, Jan 7, 2009.

  1. Blazer5913 macrumors 6502

    Jan 20, 2004
    Hello all, I have a quick question and would love your help. I came home from college this break to a load of questions from my parents regarding their iMac they use. I got most of them, but what I'm stumped on is this: they complained about their fans always being on/loud and the computer being very hot, and acting very sluggish. I was confused, so I tested it out, and in fact, the activity monitor (and istat nano) both confirmed that the CPU was maxed out at 95-100% basically always, and this was only with Firefox running; THATS IT! The fans seem loud and full blast (registering at CPU 5000. System 3000. HDD 2600rpm) and again, with only firefox running. Yet, when I check the activity monitor, although it says 100% of the CPU is being used (by user) it only says that Firefox is taking up 9.50%, and thats basically the only considerable application. I'm stumped here, and any help would be great. Here are the specs of the computer (it's a bit old, but still should not be doing this...)

    iMac G5, 1.8Ghz, 1GB Ram (which says has about 700mb free when using firefox), running OSX Tiger

    Please let me know if you of any solutions. I almost want to just back up what they need and reinstall/wipe the computer and start fresh. But thats last resort :(. Thanks
  2. Reflow macrumors 68000


    Mar 30, 2005
    My suggestion would be to add more ram. Also what other apps are open when the fans turn on at full blast. What happens when you use Safari?
  3. linuxophile macrumors regular

    Nov 8, 2005
    It is not normal. Memory does not count here.

    Things to check:
    1) which PROCESS takes up CPU time? (In Activity monitor, click on the column CPU so as to order the processes by their CPU usage). It may be just some runaway process of some application that crashed.
    2) kill that process.
    3) investigate if it is a startup item and in case remove it.

    Failing the above, try a reboot.

    I had the same machine (which died) and never had this type of problem.

Share This Page