iMac keeps locking up

Discussion in 'iMac' started by fanias, Nov 20, 2012.

  1. fanias, Nov 20, 2012
    Last edited: Nov 20, 2012

    macrumors newbie

    Nov 20, 2012
    [Update: No kidding right after I posted this it locked up again. doh....]

    Computer Details: iMac 21.5" running OSX Mountain Lion Version 10.8.2
    Processer is 2.5 GHz Intel Core i5 with 12 GB 1333 MHz DDR3 RAM

    I've had my iMac for nearly a year, all has been pretty smooth until recently when it has decided to start locking / freezing up on me (more details shortly). The only changes I have made to the system so far have been #1 I upgraded to 12 GB of aftermarket RAM from the stock 4 GB and #2 I upgraded to Mountain Lion when it became available. All of this took place pretty quickly after I bought the iMac so I don't feel that any of my changes have affected as I have been running the machine like this for nearly a year.

    What I did notice was there was an OS update about 6 weeks or more ago that was around the same time of my problem. Could have been a coincidence or not.

    When it locks up the screen just completely freezes, nothing responds at all, and often it gets stuck on the same sound.

    What I do notice though is that when I'm playing games especially more graphically intense, i.e. WoW (is the worst, will freeze up anywhere between 1 - 3 hours of gameplay) Minecraft (pretty stable for a long while, but still have had it lock up with this as well). Only once has it locked up while I was just in normal desktop non-gaming mode.

    Any help or advice would be wonderful, my 1 year warranty will be running out soon as I bought it on Black Friday of last year. :(
  2. macrumors 65816


    Oct 5, 2006
    London, United Kingdom
    Do you notice the back of the machine getting extremely hot? Also, run a disk check from disk utility to check your HDD.
  3. macrumors 6502

    Jun 19, 2010
    Oceanside, CA
    Download a system monitoring program and check the temperatures of your computer while your using it, something like iStat.

    Also do you do any type of maintenance at all on your iMac? Run the disk check like BMC recommended, and also run the "repair disk".

    How full is your HDD?

    Open up activity monitor and check the CPU processes and memory stats. Are you using up all 12GB of memory?
  4. thread starter macrumors newbie

    Nov 20, 2012
    bmcgrath: No I didn't notice that but I will definitely check that out next time it locks up.

    Thanks for the advice, in the mean time I'll run the disk check utility and will followup with results shortly.
  5. thread starter macrumors newbie

    Nov 20, 2012
    The DRis: Out of 500GB I'm only using 75GB. As for RAM I do run a server for Minecraft that me and my friends play on, I typically am dedicating about 1.5 - 2 GB of RAM for that, otherwise I'm just doing normal stuff, sometimes I do notice that it is using around 10GB of the 12 and I start closing things as much as I can when that happens. Last night it locked up on me and I restarted, then restarted the server which is ran via a JVM. This morning after posting this originally it locked up again.

    In the meantime I'll go and run the various utilities, I've already just installed iStat here is a screen shot from that as well.

    Attached Files:

  6. macrumors member

    Nov 11, 2011
    bmcgrath is on the right track, heat is likely the culprit. IMacs have some heat dissipation issues (which is why some of us are a little worried about the new model's thinness).
    I have a little fan set up to blow across the back of my machine that I turn on when I play games to help keep things from overheating. Not the most elegant solution but it works pretty well.


    PS. Buy Applecare now before your warranty ends, it's worth every penny.
  7. thread starter macrumors newbie

    Nov 20, 2012
    FuriousGreg: Yeah I've been debating about buying AppleCare, I think this pushes me over the top into making that decision.

    Everyone: Verify Disk returns results that the Disk is OK, I'm running the Repair Disk Permissions next. Will followup soon.
  8. thread starter macrumors newbie

    Nov 20, 2012
    Here are the results from these two tests.

    Verifying volume “Macintosh HD”
    Checking file systemPerforming live verification.
    Checking Journaled HFS Plus volume.
    Checking extents overflow file.
    Checking catalog file.
    Checking multi-linked files.
    Checking catalog hierarchy.
    Checking extended attributes file.
    Checking volume bitmap.
    Checking volume information.
    The volume Macintosh HD appears to be OK.

    Repairing permissions for “Macintosh HD”
    Group differs on “Library/Java”; should be 0; group is 80.
    Permissions differ on “Library/Java”; should be drwxr-xr-x ; they are drwxrwxr-x .
    Repaired “Library/Java”
    Group differs on “Library/Preferences/”; should be 80; group is 0.
    Repaired “Library/Preferences/”
    Permissions differ on “System/Library/Frameworks/CoreGraphics.framework/CoreGraphics”; should be lrwxrwxrwx ; they are lrwxr-xr-x .
    Repaired “System/Library/Frameworks/CoreGraphics.framework/CoreGraphics”
    Permissions differ on “System/Library/Frameworks/CoreGraphics.framework/Resources”; should be lrwxrwxrwx ; they are lrwxr-xr-x .
    Repaired “System/Library/Frameworks/CoreGraphics.framework/Resources”
    Permissions differ on “System/Library/Frameworks/CoreGraphics.framework/Versions/Current”; should be lrwxrwxrwx ; they are lrwxr-xr-x .
    Repaired “System/Library/Frameworks/CoreGraphics.framework/Versions/Current”
    Group differs on “private/var/db/GPURestartReporter”; should be 0; group is 80.
    Permissions differ on “private/var/db/GPURestartReporter”; should be drwxr-xr-x ; they are drwxrwxr-x .
    Repaired “private/var/db/GPURestartReporter”

    Permissions repair complete
  9. thread starter macrumors newbie

    Nov 20, 2012
    I've done some testing and it seems this definitely ONLY happens when I'm doing something graphically intensive and / or I have a server running and taking up lots of memory. It seems to me it is either a memory issue or a graphics card issue. Though sometimes it locks up without having a game running, but ONLY locks up if I'm not on a game when I have a server instance running which is using a lot of memory.

    What do you guys think?
  10. macrumors newbie

    Apr 24, 2014
    Has anyone resolved this issue? I have the exact same issue and it's driving me crazy.
  11. macrumors 68000


    Jan 21, 2008
    Melbourne, FL
    As some had said here, there can be heat issues with iMacs when doing graphic intensive tasks--like some games. I guess since the design has not changed, it can still be a problem. I had this problem with my iMac--but not with my rMBP. My iMac is from 2008 and installing SMC Fan Control did help by allowing manual adjustment of fan speed. Not sure how all that applies to current gen iMacs, but it was an issue with mine.
  12. macrumors newbie

    Apr 24, 2014
    If I took my 2012 iMac into the Apple store, would this be something they could fix? Or is it just a given based on bad design? The problem is, I hadn't experienced this up until a few weeks ago.

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