Late 2007 iMac 20" Freezes completely random.

Discussion in 'iMac' started by Naad, Oct 25, 2011.

  1. macrumors newbie

    Joined:
    Jan 4, 2010
    #1
    Hello everyone,

    I have at the moment an iMac 2.0ghz 2gb ram, 20 inch from 2007 which has problems.
    The problem is that once in a while the machine just freezes. Everything is stuck, except for the mouse for some weird reason. Also I am able to connect to the iMac via the network (connection established after freeze), and able to copy files from the iMac.

    This does not happen under particular circumstances (or at least I do not know of them yet..)

    The iMac has been to an authorized service provider here in the Netherlands, however they said it could be the lcd, graphics card or the logic board..

    I have tested the iMac with Apple Service Diagnostics, and it doesn't show an error.. Techtool Pro 6 passes everything. Running ram tests with Rember for extended periods of time also is fine. A CPUtest running at max cpu runs fine as well.. CPU usually stays below 60 degrees celsius.

    My next step is completely formatting the harddrive and either reinstall 10.6.8 (which is on there now btw) or go for lion.

    Long story in a short question -> What could cause freezes where the harddrive is accesible through the network and the mouse can move, but nothing works?

    Any other ideas of what I should do?
     
  2. macrumors newbie

    darthkarl

    Joined:
    Oct 24, 2007
    Location:
    Wyoming
    #2
    I have the exact same problem with a late 2009 27" iMac (i7, 8 Gigs). I keep it running 24/7 and it was an extremely stable machine with snow leopard (I think I had a run once of 48 days or so without a reboot). However apparently with the upgrade to Lion I've had a lot of random freezes just like the original poster has described. It seems to happen every 2 to 3 days. Usually freezes up on the screensaver, but I still have an active mouse on screen.

    I have replaced the hard drive and reinstalled all of my data, but to no avail. I'm thinking now of replacing the RAM to see if that helps. Any other ideas out there?
     
  3. macrumors newbie

    Joined:
    Nov 26, 2011
    #3
    2007 iMac freeze issue

    Im having the exact same problem. Works fine in 10.6 but freezes constantly with 10.6.8. Cant even use the computer because it crashes so frequently.

    I just installed a fresh hard drive and did a clean os install but still have the same problem.

    Anyone have any other suggestions?
     
  4. Intell, Nov 26, 2011
    Last edited: Dec 2, 2011

    macrumors P6

    Intell

    Joined:
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    Location:
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    #4
    My 2007 Al iMac does this as well. I haven't pinpointed the cause yet, but I'm narrowing it down. So far I know:

    It only happens on 10.6.8, not 10.6.7
    Its related to a GPU crash/failure/panic with the ATI 2400/2600 GPU
    Works properly for a few days after a system reinstall or a clearing of caches
    Works properly if running in Safe Boot/Mode
    Not caused by any third party kext
    Will still crash on a clean 10.6.8 installation
    I believe its caused/exacerbated by Core Image
    Loading a remote computer's screen for the first time in Remote Desktop seems to trigger the crash often, but not always


    I'll post more information as I probe into my crashes and system logs.
     
  5. macrumors newbie

    Joined:
    Nov 26, 2011
    #5
    iMac freezing with 10.6.8

    I noticed one other oddity, I have a fresh install of 10.6.8 on a brand new hard drive and when I repair permissions it constantly finds issues to repair. Even when I run it 5 times in a row, it seems to be repairing the same files?

    maybe try that on your computer and see if it does the same.

    I'm almost ready to give up. Even when I install Lion the random freezing issue from 10.6.8 still happens, maybe even worsen.
     
  6. macrumors P6

    Intell

    Joined:
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    Location:
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    #6
    There are some files that have the correct permissions even when Disk Utility says they are incorrect. Some of these files include Java stuff and ARD stuff. It is safe to ignore these errors.
     
  7. macrumors newbie

    Joined:
    Nov 26, 2011
    #7
    still freezes after another clean os install

    Hey Intell you mentioned that you dont get any freezes in 10.7? Mine still freezes constantly even with 10.7.2, I'm thinking of going back to Snow Leopard 10.6.7 and keep it there until someone figures out what the problem is.

    Anyone have any other suggestions? This is really driving me crazy...
     
  8. macrumors P6

    Intell

    Joined:
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    #8
    I only lightly tested mine on 10.7.2. So there may have been some crashes. I am currently experimenting with some extensions hoping for a fix.
     
  9. macrumors P6

    Intell

    Joined:
    Jan 24, 2010
    Location:
    Inside
    #9
    Whose wanting to try a fix? I've done this to my system and it hasn't crashed with 2+ days of uptime.

    Make a new folder on your Desktop called "Old Extensions". Put the following extensions from /System/Library/Extensions into it: ATI4600Controller.kext, ATI5000Controller.kext, ATI6000Controller.kext, ATIRadeonX3000.kext, ATIRadeonX3000GA.plugin, ATIRadeonX3000GLDriver.bundle, ATIRadeonX3000VADriver.bundle. Restart your Mac into Safe Boot by holding down the shift key. When the Mac has finished booting into Safe Boot, restart it normally. Run this command in Terminal "sudo kextcache -system-mkext". When its done, restart your Mac again, that's it. If you want, save/backup/delete the "Old Extensions" folder.

    Note: I have an ATI 2400HD video card. This fix will not fix non-ATI GPU related crashes. If you have an ATI GPU that matches one of the removed extensions, don't do this.
     
  10. macrumors newbie

    Joined:
    Dec 2, 2011
    #10
    I dont have any of those however i have the same graphics card as you. i have from top to bottom in my extensions folder ATIRadeonX2000VADriver.bundle ATIRadeonX2000GLDriver.bundle ATIRadeonX2000GA.plugin ATIRadeonX2000.kext ATIRadeonX1000VADriver.bundle ATIRadeonX1000GLDrive.bundle ATIRadeonX1000GA.plugin ATIRadeonX1000.kext ATIRadeonGLDriver.bundle ATIRadeonGA.plugin ATIRadeonDVDDriver.bundle ATIRadeon9700VADriver.bundle ATIRadeon9700GLDrive.bundle ATIRadeon9700GA.plugin ATIRadeonDVD9700Driver.bundle ATIRadeon9700.kext ATIRadeon8500VADriver.bundle ATIRadeon8500GLDrive.bundle ATIRadeon8500GA.plugin ATIRadeonDVD8500Driver.bundle ATIRadeon8500.kext ATIRadeon.kext ATINDRV.kext
     
  11. macrumors P6

    Intell

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    #11
    Some of those are not Snow Leopard kexts. What version of Mac OS X are you running?
     
  12. macrumors P6

    Intell

    Joined:
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    #12
    Update: My proposed fixed apparently didn't work. Still trying to pinpoint the exact extension(s) that cause this failure to occur.
     
  13. macrumors 68000

    Joined:
    Sep 10, 2008
    Location:
    Asheville, NC
    #13
    You're assuming it's the extensions that are causing the failure and not the graphics card itself. If you can get the the thing not to crash by not loading drivers for your video card, then you'll have a stable system with absolutely no hardware acceleration. Why not just get the graphics card replaced?
     
  14. macrumors P6

    Intell

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    #14
    Because it runs fine with 10.6.7 extensions on a 10.6.8 system with full hardware acceleration. It also has no problems in Windows via Boot Camp.
     
  15. macrumors newbie

    Joined:
    Dec 9, 2011
    #15
    Okay, for what it's worth, I seem to have fixed my freeze problem with my early 2008 iMac. I was reading on another site about how it might be caused by a graphics chip getting overly hot and they recommended trying this:

    http://www.macupdate.com/app/mac/23137/fan-control

    I tweaked the fan speed up a couple of times and now have not had a freeze in about two weeks.

    Worth a try, I suppose.

    At about the same time I also disconnected from the DSL and have just been using it wirelessly, but I think it froze once after doing that, so I don't think that has anything to do with it. Maybe I should reconnect and see what happens.

    Bill
     
  16. macrumors 68000

    musio

    Joined:
    Jun 2, 2008
    #16
  17. macrumors newbie

    Joined:
    Dec 9, 2011
    #17
    And I don't recall having any issue until upgrading to SL a few months ago. It seems that it's often an issue with upgrading. I reconnected the DSL. If it freezes, then I'll report back. I don't see what that would have to do with it, though. It was to the point of freezing a couple of times a day, so the fact that it's not done so in two weeks means that something I've done has worked (hopefully).
     
  18. macrumors P6

    Intell

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    #18
    This isn't like your problem. With these kinds of crashes there is not kernel panic. Only a frozen system that's stuck in a GPU debugging mode of some kind. Of all the Internet searching I've done on this problem, it seems to only happen with Snow Leopard and Lion Macs with ATI 2400/2600 video cards.
     
  19. macrumors newbie

    Joined:
    Jan 5, 2012
    #19
    Hi I have a mid-2007 aluminum imac 20" and spent the last months exactly with the same random freeze problem described by many on this thread, specially when waking my mac from sleep, the mouse moves but nothing happens.
    In my case I narrowed the problem to be something related to my ATI RadeonHD 2400 XT and the last updates for SL.

    First the freeze happened occasionally, then evolved to happen from around 20min in 20min and it did not matter which app I was using, sometimes I was just staring at my desktop.

    I spent November and December doing an exhaustive troubleshooting and at last took it to repair to see if it was my hardware.They returned it and said my hardware was perfect. I did a clean install, upgraded again to 10.6.8 and brought my docs from my backup without using time machine nor migration assistant. Then I installed all my apps from scratch.

    It got better but the freeze still happened. I thought it was Little Snitch and uninstalled it, then it happened with Thunderbird and I uninstalled it, at the end, because sometimes I was getting a odd glitch on graphic display(brief instances of pixel artifacts on icons) specially when using Firefox, I turned off hardware acceleration on this browser, the glitch disappeared and that was when I thought it could be related to my ATI.
    Even though, 2 days ago after waking the mac from sleep 5 mins after, I got a black screen.

    I am still trying to find a fix related to this problem as there is no update for my ATI.
     
  20. macrumors 6502

    Joined:
    Oct 18, 2005
    #20
    after upgrading my 2007-Al 24 inch iMac to 10.7 it ran like crap and would freeze up at times. I just recently upped the RAM from 2gbs to 4gbs and its a million times better. almost like a new computer. the 2gigs of RAM that ran 10.5 fine did not run 10.7 well at all. the best $50 upgrade i could do.
     
  21. macrumors P6

    Intell

    Joined:
    Jan 24, 2010
    Location:
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    #21
    I have a small update to my own crashings. I recently upgraded my iMac's ram from 2Gb to 4Gb and it's been on for 9 days with no crashing. Its possible that reseating or upgrading the ram in an effected iMac could solve this problem. Another problem could be bad ram. But both of these ram causes are very unlikely as the crashes don't happen on older Mac OS X versions. Only 10.6.7/.8 and above.

    I also know that a 10.6.8 system with 10.6.7 extensions still crashes. Haven't tried 10.6.6 extensions though. It's also possible that the crashing isn't caused by an extension, but rather some other updated file. It could even be the kernel itself that is causing the crashes.

    I'd also like to reiterate that heat is not the cause of the crashing. My iMac has been running at 100% do video encoding for the 9 days with the fans set at the default speed and I have yet to get a crash, even while it is very warm to the touch.
     
  22. BlueCobalt, Jan 6, 2012
    Last edited: Jan 8, 2012

    macrumors newbie

    Joined:
    Jan 5, 2012
    #22
    Somehow I managed to clear the issue and now it is all working fine...
     
  23. macrumors P6

    Intell

    Joined:
    Jan 24, 2010
    Location:
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    #23
    Small update. I had another GPU crash today. Uptime 11 days and 5 hours. Most of the time the CPU was running at 100% and the fans where at their stock speed. I believe the additional 2Gb of ram for a total of 4Gb of ram allowed me to surpass my previous uptime before crash by 5 days.
     
  24. macrumors newbie

    Joined:
    Jan 30, 2012
    #24
    I have the same iMac same Video Card and same exact issues. I have been struggling with this issue for a while.

    I already had 4Gb of RAM before the issue and have changed back to 2GB and right now am on 3 GB but the issues are just the same.

    I just installed Fan Control and noticed something odd. It shows my Temps have a negative value. -127.0C! I find this highly unlikely.

    [​IMG]

    Anyway, I bumped the fan speed upto 300RPM to possibly compensate and test.

    I was running 10.7.2 and now am on a fresh formatted drive with 10.6.8 and still have the same issue. If it continues I will reinstall SL and NOT install all the updates to get to 10.6.8 but stay on an older version
     
  25. macrumors P6

    Intell

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    #25
    Your image is broken. I'm very confiden that heat is not the cause of these freezings. If you do go back to Snow Leopard, 10.6.6 is the last freeze free version that works for me.
     

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