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24" iMac Screen Freezes since 10.6.3 update - pls help!

454903 Views 1,593 Replies Latest reply: Mar 5, 2014 4:31 PM by forevermacintoe RSS Branched to a new discussion.
  • TK111 Level 1 Level 1 (0 points)
    Currently Being Moderated
    Mar 16, 2012 1:31 PM (in response to CW3X)

    Well, if you can get a new GPU for free, I'd say do it. Mine still works great without the kext fix.

  • Ken Cluff Calculating status...
    Currently Being Moderated
    Mar 16, 2012 2:02 PM (in response to CW3X)

    As someone who's applied the kext fix up to Lion (10.7.3), on an iMac 7,1 I can tell you it works just fine at least that far. 10.7.3 supposedly had some fixes for older ATI cards, which my imac has, but it didn't help. You can upgrade that far without a problem. I imagine, I'll be able to ride Lion as far as it will go at this point. Mountain Lion is another story, but I'm hopefull, it will work on it too.

  • CW3X Calculating status...

    @Fritos_Chips:I bought it as a refurb from Apple in March 2009.


    @TK111: Any tips on what to say to get Apple to replace the GPU?

  • TK111 Level 1 Level 1 (0 points)
    Currently Being Moderated
    Mar 16, 2012 2:23 PM (in response to CW3X)

    I had gotten upset about all the freezes, so I started documenting each time it happened for about six months. It was, as you probably know, several times a week, sometimes several times a day. That seemed to sway their decision. Not much help if you haven't done that, but just my experience.

  • Tardigrada Calculating status...

    TK111 wrote:


    You're right. The kext fixes worked for me, but I also got a new GPU (ATI 2600 Pro) under Apple Care 9 months ago and haven't had a problem since then even with the new kexts. Yippee! The cost would have been $179 for the GPU otherwise.

    Where do you get the GPU for $179? Couldn't find anything below $268 …

  • TK111 Level 1 Level 1 (0 points)

    I got it under AppleCare, fixed at the Apple Store. $179 was what it said on the receipt, but I suppose labor would have been on top of that if I'd had to pay for it. Don't know about prices on the open market.

  • Brian from VA Level 1 Level 1 (10 points)

    CW3X, I also have an iMac 8,1 running 10.6.8 in 64-bit mode with the kext fix (which has been working well).  From what I've seen reported, I'm resonably confident of the kext fix working through all the Lion releases, and maybe Mountain Lion, too. 


    Having said that, if mine were still under AppleCare, I would seek out a replacement GPU.  Partly for the Mountain Lion uncertainty, and more because I might want to sell the machine someday.  Can you imagine saying to a potential buyer "Well, after each OS X release, you'll have to copy these old system kernel extension files over, and...?"  Kinda detracts from the "It just works" idea.

  • crinfante Calculating status...

    While it was still under AppleCare, I took my iMac in for service on 3 different occasions, and since they couldn't reproduce the problem during their hardware test they said I was out of luck. I also have talked with Apple support on the phone multiple times and after they said they would get back to me, but they never did.


    This is exactly my problem -- I would like to sell my iMac and upgrade, but I feel I can't without getting this problem fixed first. It appears that whether the GPU gets switched out or not under AppleCare is a random result based on how the service employee feels. I'm debating trying to take the computer to an Apple Store, update the computer in front of them so that the kext files get overwritten, and then working at the store until it freezes. Or suing Apple in small claims court...

  • Fritos_Chips Calculating status...

    I finally got the time to take a picture and post



  • Fritos_Chips Level 1 Level 1 (0 points)

    I've now down graded all the way to Leopard.  I'll just stick with this old OS until someone posts that Apple has fixed our issue.


    I tried Windows 8 recently.  That alternative isn't looking too good either.  I might just go back to Windows 7 altogether...

  • thoniefromgroningen Calculating status...

    Since i installed Lion (went from leopard to lion) my iMac 8,1 early 2008 Ati 2600 HD has the same problem as described  here.


    It started with the black or green screen with lines crash. After upgrading to 10.7.3 it started to freeze (could only move the mouse).


    The solution to this problem was to install the 10.7.3 combo update (it puts a "d" after the serial number when correct installed) But now the black or green screen with lines crash is back:(


    anyone tried the old kext files fix on 10.7.3 with the combo update?

  • thoniefromgroningen Level 1 Level 1 (0 points)

    I also found this solution


    "Apparently Snow Leopard drives the GPU harder than Leopard does, but runs the iMac’s fans at the same barely-audible speeds. The problem is more likely to occur on iMacs that are left on all the time, as mine is."


    did not tried this yet...

  • Eclipsethegalaxy Level 1 Level 1 (5 points)

    I stated in this thread some time ago about 'Fan Control for Mac'. It worked for me to a point. By cooling down the GPU I reduced the number of times my computer would act up. But it did NOT totally eliminate the problem. I had my GPU replaced 3 weeks ago under APPLE CARE.  No more freeze ups. The GPU that I had replaced was the GeForce GT 130 by NVIDIA. This must have been a revised card as it was the same model as I had when I purchased my computer. Since the card was replaced I turned my fan speeds back down and have not had any problems. I am able to multitask graphics driven apps with ease.

  • Simon Baker Calculating status...

    My latest - with some interaction with the bug team - suggest everyone with a problem uses that (noting discussions are not a formal means of submitting bugs):


    Hi Simon,


    This is a follow-up regarding Bug ID# 8659522.  


    Please update your report directly at for the fastest response.  Please do not email your updates.


    Engineering has requested the following information in order to further investigate this issue:


    Can you please attach the GPU hang log that you saw in 10.7.3 for us?


    Can you attach kernel.log containing  GPU Debug info start to End?


    Bug reports requiring your attention will appear under ‘My Originated Problems’.  Please review this bug report and provide the requested information via the Apple Bug Reporter at  Once your report has been updated, Engineering will be alerted of the new information.


    Thank you for your assistance in helping us discover and isolate bugs within our products.


    Best Regards,


    Developer Bug Reporting Team

    Apple Worldwide Developer Relations


    ******************************************************************************** **************


    ******************************************************************************** **************


    Bug ID #: 8659522

    Bug Title: Freezing iMac8,1


    <GMT11-Nov-2010 23:24:38GMT>

    Summary: Seemingly random freezes since 10.6.3 update on iMac 8,1 (duo 2.66GHz ATI HD2600 Pro. running fans at 1500+ rpm via SMCFanControl appears to reduce the freezing instances.


    Steps to Reproduce: Run OSX 10.6.3+ for up to 24 hours. Safari and Mail always running, but no real pattern. Sometimes complete lock, sometimes cursor can be moved. Sometime there is a SLOT--1 GPU Debug info from Console (copy below) but it never recovers control. Many similar issues reported on Discussions


    Expected Results: I expected my computer to behave like a reliable, sweet computer.


    Actual Results: My computer goes away somewhere and ignores me.


    Regression: I wish I could tell, but it is frustratingly random, unless I resort to 10.6.2 then all is fine and dandy.


    Notes: SMCFanControl at 1500+ seems to reduce the number of occurrences for me.


    Attached should be a debug sample from Console: (I have some other lists if this grabs you, but this is not reported for every freeze.


    (PS I did not find it easy to let Apple know about this problem as I couldn't find this page on Support, and the crashes did not trigger an issue to "Report to Apple")




    <GMT16-Jan-2011 17:09:32GMT>

    Many thanks for getting back to me.

    I have run AHT several times since the issues first occurred in the late Spring. Sometimes passes, sometimes reports 4MOT/1/40000003 HDD - 1xxx (the number changes between about 1200 and 1350) I understand this to be a HDD fan drive over speed (?) from forums, and iStat pro normally reports the exact same fan speed for the Hard Disk Drive. It usually reports ok if I run it first thing in the morning after leaving it all unplugged.


    No other issues or failures reported.






    <GMT04-Apr-2011 20:42:23GMT>

    Mine is an iMac8,1 system serial YM836***ZE3. Crashes always involve Safari as a minimum (usually with Mail in the background). However, if I do a software update or set up as a new user on anything beyond 10.6.2 it works faultlessly for about 3, maybe 4 days. Then freezes start, sometimes with mouse movements and a frozen screen (time stuck), sometimes screen switches to some blank or lined screen. Hard reset required, then freezes every few hours. Sometimes GPU crash log recorded by Console, sometimes not.

    SmcFanControl did appear to alleviate the problem, so one might think it was a temperature/hardware issue, but the new user/new update and ~4 days fault free operation would make you think it might be a memory leak? Who knows? Only thing for certain is that the 10.6.2 drivers get around the issue. But I guess a lot of iMacs must be unaffected, else it would be reported more widely? So maybe just a limited hardware version? Or perhaps a corrupt firmware issue (don't know how to reset that one?). Other resets don't change behaviour (SMC, PRAM). All very strange, very annoying/disappointing/frustrating. Si


    <GMT28-Jun-2011 21:51:05GMT>

    Jeez. Check out the support thread: [iMac (Intel)] - Re: 24" iMac Screen Freezes since 10.6.3 update - pls help!


    as it reports that the 10.6.2 ATI driver "hack" does not appear to work under 10.6.8 for the many users there. I have not updated due to that thread's experience. We cannot believe that it can be a hardware issue as it is only apparent for the drivers beyond 10.6.2. What a terrible experience. Makes some of use impressed that windows can work under so many different hardware configurations and drivers where as Apple does not seem to be able to resolve its own hardware.


    If you like I could try 10.6.8 and submit any crash logs, but as it didn't seem to enlighten anyone your end I guess it would be a waste of my time…


    How about a new Apple Logo "never buy a mac without Applecare, else we won't care!"


    <GMT07-Nov-2011 22:30:44GMT>

    This issue has been verified as resolved and can be closed.


    <GMT07-Nov-2011 22:30:58GMT>

    This issue has been verified as resolved and can be closed.


    <GMT07-Nov-2011 22:31:09GMT>

    This issue has been verified as resolved and can be closed.


    <GMT07-Nov-2011 22:35:39GMT>

    Hi, I am extremely pleased to report that with the latest Lion release 10.7.2, I have not had to hack the ATI2600 kext files back to 10.6.2 and everything appears stable. No freezes after 6 days without a restart, and now 10 days without a restart.


    For information, the Apple Support community thread is still reporting some freezes to a mix of machines.




    <GMT09-Feb-2012 22:18:49GMT>

    Oh bother. Release 10.7.3 has gone back to exhibiting the exact same issue as every update since 10.6.2 EXCEPT 10.7.2, White screen or frozen screen (usually with cursor still moving ok, but nothing else changing on the screen and no clicks or keyboard entries being processed. Sometimes with a GPU debug log registered, sometimes not ) I attach the system report with this for your edification.

    From the discussion forums, I seem to be the only one who had success with 10.7.2 - everyone else was reverting the 3 kexts for ATI to 10.6.2 versions for a stable machine. I tried the same with the 10.7.2 kexts, but with no success - freezy time - and frustratingly I didn't keep a system back of 10.7.2 before the update, which with the Lion installer I now have no way of reverting back to 10.7.2 from 10.7.3. RATS, RATS, RATS.


    I see from the discussion forums that other machines (MacBook Pro and Man mini) also have freezing issues and next fixes reported. Obviously it is not every machine, but it is bizarre. I trust that your machine build configuration control is as robust as can be - Apple develop the hardware and the software but still seem to be tripping up with the GPUs? Some have success with Applecare logic board replacements - but it is odd that a software fix would work around the hardware, unless it is a configuration issue?


    Been nearly 2 years now, these machines aren't cheap and are otherwise fantastic. I really hope that the answer to this is not the Lion autosave feature…


    <GMT09-Feb-2012 22:18:50GMT>

    'iMac' was successfully uploaded

  • Rafael Burgos Calculating status...

    Thank you for the update.  Just today I followed your suggestion and filed a bug report with the specifics for my machine, a mid 2007 20 inch iMac 2.0 GHZ Core 2 Duo with 4 gigabytes of RAM and an ATI Radeon HD 2400 XT with 128 Mb of video RAM.


    Here is the text of my submission:


    iMac (intel) mid 2007, 20 inch with 4 gigabytes of RAM, ATI Radeon HD 2400 XT (128 Mb) video card running without problems on Mac OS X 10.5.8 is upgraded to Mac OS X 10.6.8 or Mac OS X 10.7.3 and the display freezes/crashes repeatedly rendering system unusable.


    Steps to Reproduce:

    Clean install of 10.6.0, then update to 10.6.8


    Clean install of 10.6.0, then update to 10.6.8, then upgrade to 10.7.3


    Clean install of 10.7.3 using bootable USB stick


    Expected Results:

    Normal video display operation


    Actual Results:

    -Repetitive video freezes, mouse can usually be moved on the screen but cannot interact with GUI elements, only way out is to do a forced shut-down using the power button. Intermittent spinning "beach-ball"

    -Noticeable graphical distortions affecting various display elements (buttons, icons, finder text) up to totally garbled/distorted display.

    -Sometimes the freeze will not even allow for login, sometimes it will happen within seconds or up to several minutes of login.

    - When able to get screenshots, graphical distortions are recorded on the saved image.

    - If the computer is left alone, eventually it *does* become responsive (sometimes after several hours) but the display is totally garbled and user can not interact with GUI, again a forced shut down is the only option at this point.



    Problem occurs when starting up in "normal" mode.

    Problem occurs when starting from the internal drive or from a drive attached via USB or FireWire.

    Does not occur when starting up in safe mode.

    Does not occur when starting up in Mac OS X 10.6.0



    1.  References to related problems:  See Apple Discussion thread

    2.  Effective workaround: See page 28 of above Apple discussion thread at adapted from  Involves downgrading the video card drivers or kexts to those of Mac OS X 10.6.2.

    3.  When the computer is frozen and remote login has been activated previously, I can SSH into the iMac from another Macintosh system in the same network and can issue commands and get expected responses from the terminal.

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