[iMac 27"] CPU Idle Usage 100% at all times

Discussion in 'iMac' started by Vortor, Feb 18, 2012.

  1. Vortor, Feb 18, 2012
    Last edited: Feb 18, 2012

    Vortor macrumors newbie

    Joined:
    Jun 19, 2010
    #1
    Hi all,

    Around May 2010, I ordered a 27" iMac (Mac OS X 10.6.8) with the following specs:

    Code:
    PROCESSOR 2.8GHZ QUAD-CORE INTEL CORE I7
    MEMORY 4GB 1066MHZ DDR3 SDRAM - 2X2GB
    HARD DRIVE 1TB SERIAL ATA DRIVE
    GRAPHICS ATI RADEON HD 4850 512MB
    OPTICAL DRIVE 8X DOUBLE-LAYER SUPERDRIVE
    MOUSE APPLE MAGIC MOUSE-Z
    APPLE SOFTWARE - IWORK NONE
    APPLE SOFTWARE - FINAL CUT EXP NONE
    APPLE SOFTWARE - APERTURE NONE
    APPLE SOFTWARE - LOGIC EXPR NONE
    APPLE SOFTWARE - FILEMAKER NONE
    APPLE SOFTWARE - MS OFFICE NONE
    APPLE KEYBOARD & USER'S GUIDE WL KYBD & USER'S GUIDE-PO
    COUNTRY KIT COUNTRY KIT,IMAC 27-INCH-PRT
    
    Until yesterday everything was running smoothly, but around midnight the electricity went out, came back for a split second and was gone again. After that, I took out the plug from the electrical outlet and went to sleep.

    When I woke up this morning and turned on the computer, I noticed it took much longer than usual to boot. Also, it took a few additional minutes for the "I'm doing too many task at once" noise to go away.

    Besides playing Starcraft 2 on low graphics, using a bit of Photoshop here and there, the occasional Screenflow high definition desktop recording and Premiere video editing, I don't do much cpu intensive tasks these days.

    A user somewhere recommended to go to System Preferences > Startup Disk > Select Disk and click Restart. And it seems it solved the issue. At least, the boot is faster now. I decided to reset my PRAM and NVRAM. I'm not sure if it helped, but now the boot takes only around 30 seconds. I'm happy.

    Still, my CPU idle usage is still at 90-100% all the time, even when I have no applications open? Is this normal?

    I turned off Airport to see if the high % idle CPU usage would go down. No luck. After that, I checked Activity Monitor > All Processes. Everything seems fine, most of the values don't even reach 0.5% CPU usage. The top processes (usually Activity Monitor or Google Chrome) spike at 4-5% usage for a split second.

    Maybe I'm overreacting, but I just want to be sure this couldn't cause some future problems, especially because the warranty is almost over.

    Thanks for the help.

    P.S: Not sure if it helps, but here's a screenshot from iStat Pro with only Google Chrome open.


    Edit: Added screenshot.
     

    Attached Files:

  2. miles01110 macrumors Core

    miles01110

    Joined:
    Jul 24, 2006
    Location:
    The Ivory Tower (I'm not coming down)
    #2
    Launch Activity Monitor, select "All Processes", sort by CPU, and kill whatever is taking up so much CPU.
     
  3. Vortor thread starter macrumors newbie

    Joined:
    Jun 19, 2010
    #3
    I did that. The values are constantly changing, but most of the time the top processes that use more CPU are the Activity Monitor and Google Chrome with 0.8 - 3%.

    iStat Pro still shows a constant 99-100% idle CPU usage. User, System and Nice stay at 0.

    I did some research on the web. I don't know where it was but there was a person with same problem. One user said there could be a problem with the core.
     
  4. AdrianK, Feb 18, 2012
    Last edited: Feb 18, 2012

    AdrianK macrumors 68020

    Joined:
    Feb 19, 2011
    #4
    It means your CPU is 100% idle. As confirmed by activity monitor. Idle is that state where the processor isn't doing anything.
     
  5. Bear macrumors G3

    Joined:
    Jul 23, 2002
    Location:
    Sol III - Terra
    #5
    I think we have a failure to understand terminology here. :D

    If a system has "100% Idle" usage, that means it's idle, that is nothing is using the CPU.
     
  6. Vortor thread starter macrumors newbie

    Joined:
    Jun 19, 2010
    #6
    Oh crap, I feel embarrassed. Somehow my brain decided 100% idle cpu usage = 100% CPU usage. I just looked at "100%" and "CPU" and ignored the "idle".

    The worst part is, the moment I read AdrianK's reply my second neuron started working and I immediately realized the stupid mistake I made.

    Oh well, thanks anyway for the help. :D
     
  7. jwm2 macrumors regular

    Joined:
    Jan 5, 2012
    #7
    Mine is typically at 97-98% idle, even with several apps open and some widgets on my secondary screen. These iMacs seem to have plenty of processing power, i rarely see mine go above 20-30% under heavy loads.
     
  8. WilliamG macrumors G3

    Joined:
    Mar 29, 2008
    Location:
    Seattle
    #8
    At this point, get a UPS. I couldn't imagine running my iMac without one.
     

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