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  • Om_Audio Level 1 (15 points)

    Hi there,

    Same issue here, kernel panic or black screen/freeze mainly with Flash vid but also when using PS etc.

    Mid 2011 27" OS X 10.7.x, maxed out with i7 and max gpu- been crashing since week we got it. Upgraded to 16GB of Crucial RAM, same issue.

    Just took it in and they say they cannot reproduce the problem which is unimaginable- we can cause the issue easily within 5 or 10 minutes.

    The repair rep didn't care about this support thread or the possibility of gpu firmware. VERY frustrating.

    Too bad we waited so long to take it in but need the machine for freelance design work. We will buy extended AppleCare and try again to get video of issue as it occurs and log when it occurs.

    I am a repair tech myself so the option of upgrading the gpu firmware is an option but i don't want to void the warranty or make things worse. If there were a free way to do it without opening the machine i would do it.


    Did you get anywhere with contacting corporate? i'd like to explore that possibility as well.




  • Om_Audio Level 1 (15 points)

    You can always file a complaint with the BBB, it is a rating that some companies will actually work to resolve the complaints that are filed.


  • S3pio Level 1 (0 points)

    I do this and work for me, I start to test for my selft when I see apple ingeniers don't do nothing for fixed.


    Follow this link

    Important do the backup and after don't return the backup just transfer the file you use manually


  • S3pio Level 1 (0 points)

    Sorry engeniers

  • paulmcg123 Level 1 (0 points)

    27" Late 2009 iMac.


    I've  been running OK for 2 weeks after reinstalling Lion and avoiding Safari and Chrome, getting complacent that I had fixed it for good, then I did a very, very stupid thing.


    I installed the most recent Safari update!


    Now it will ONLY boot properly when I boot up in Safe Mode. Checked /var/log/kernel.log via PuTTy and its the GPU error back again.

    I'm going to do Lion Recovery/Reinstall Lion thing again tonight to see if that fixes it, if not I may try S3pio's solution, complete format and reinstall.


    Its like I can't afford to accept any Apple software updates, for fear of breakign my iMac. I'm still trying to get a new HD through the update HD replacement program, so far they have only offered a refund for the drive I installed myself back in January, but of course I can't find the receipt, and I would rather a new, Apple approved HD instead.

  • paulmcg123 Level 1 (0 points)

    27" late 2009 iMac Lion 10.7.5 with ATI Radeon HD4800


    Over the past few weeks, I've done Lion Recovery, reformat and fresh install of Lion (with a new user), reinstalled from last working backup, but nothing has worked. I was still only able to boot into a graphical environment in Safe Mode, any attempt at normal boot up left me with a white screen and the GPU errors in /var/log/kernel.log (I have ethernet and am using PuTTY from a Windows 7 laptop).


    A lot of the discussions seem to centre around hardware faults, e.g. need to replace memory, logic board, graphics card, hard drive, or just the poor design of the iMac that causes overheating in the GPU.

    What ****** me off is that I have had no issues with any of this until I applied Apple's 10.7.5 software update in mid October 2012, and having a $2,000+ machine with other paid for software (Lion, Parallels Desktop, etc.) that I can no longer use. I've seen no indication anywhere that Apple acknowledges this issue or is working on a fix for the many  frustrated iMac owners who have been affected.


    Firstly, it seems you need to install smcFanControl to keep you system properly cooled - already had that for 10 months.


    Next, prevent launchd from loading any user specific programs - did that, no improvement.

    E.g. rename

    mv /Library/LaunchDaemons  /Library/X.LaunchDaemons

    mv /Library/LaunchAgents  /Library/X.LaunchAgents

    and reboot.


    Next, disable Quartz Extreme, maybe keep things a little cooler - did that, no improvement. e.g.

    defaults write /Library/Preferences/ GLCompositor -dict tileHeight -int 0 tileWidth -int 0

    to re-enable

    defaults delete /Library/Preferences/ GLCompositor


    Next, maybe its the new version of the ATI graphics kexts in /System/Library/Extensions ? 

    So, downloaded Kext Wizard and installed the 10.6.2 versions of the relevant ATI kexts, ATI4800Controller.kext, ATIFramebuffer.kext, and ATISupport.kext - did that, no improvement.


    One or more of the above have worked for some people, but not for everyone, and not for me.


    So, booted up in Safe Mode, then normally, connecting with PuTTY and saved the output of kextstat to a text file to compare.

    In normal boot (with the white screen), my ATI4800Controller.kext, ATIFramebuffer.kext, and ATISupport.kext were loaded, same as in Safe Mode, but I also noticed ATIRadeonX2000.kext - ***? That's not even my graphic card!

    Booted up in Safe Mode and made a backup of all the ATIRadeonX????*.kext and .bundles and deleted them from /System/Library/Extensions.


    Reboot in normal mode, and for the first time in 3 F@!#$ng weeks I am up and running normally! Next, start backing the other fixes out one by one to see if I can break it again.


    First, reinstalled the 10.7.5 versions of ATI4800Controller.kext, ATIFramebuffer.kext, and ATISupport.kext. Rebooted and all good!


    Second, re-enable launching of all per user specific stuff,

    mv /Library/X.LaunchDaemons  /Library/LaunchDaemons,

    mv /Library/X.LaunchAgents  /Library/LaunchAgents   

    Reboot and all good!


    Next, re-enable Quartz Extreme. Reboot and all good!

    defaults delete /Library/Preferences/ GLCompositor


    So after reversing most of my fixes, I am left with smcFanControl and the deleted ATIRadeonX???? .kexts and .bundles. I'm going to keep the smcFanControl, since my iMac gets very warm without it.


    This leads me to believe that the ATIRadeonX2000.kext, which I assume is for a laptop, was loading on my iMac, as well as the desktop version ATI4800Controller.kext. Perhaps the device ID's or something in info.plist are the same....


    pauls-imac:~ root# defaults read /System/Library/Extensions/ATI4800Controller.kext/Contents/Info.plist IOKitPersonalities | grep IOPCIMatch

            IOPCIMatch = "0x94401002 0x944a1002";


    pauls-imac:~ root# defaults read /Volumes/Scratch/kexts_uninstalled/ATIRadeonX2000.kext/Contents/Info.plist IOKitPersonalities | grep IOPCIMatch

            IOPCIMatch = "0x94001002 0x94011002 0x94021002 0x94031002 0x95811002 0x95831002 0x95881002 0x94c81002 0x94c91002 0x95001002 0x95011002 0x95051002 0x95071002 0x95041002 0x95061002 0x95981002 0x94881002 0x95991002 0x95911002 0x95931002 0x94401002 0x94421002 0x944A1002 0x945A1002 0x94901002 0x949E1002 0x94801002 0x95401002 0x95411002 0x954E1002 0x954F1002 0x95521002 0x95531002 0x94a01002";


    OK, I'm not a highly paid Apple engineer, but something doesn't look right here. Both have a reference to 0x94401002 and 0x944a1002 (0x944A1002), that's got to create some kind of conflict right there.


    I checked all the other ATI????Controller.kext/Contents/Info.plist against all the ATIRadeonX???.kext/Contents/Info.plist, and ALL have duplicate IOPCI references. Could this be an issue?


    Anyway, if you are on an iMac, you could try just deleting all the ATI RadeonX*.* from /System/Library/Preferences and see it fixes the issue, as it has for me.

    Since doing this I have not seen the dreaded lines in my /var/logs/kernel.log

    Oct  7 14:47:31 pauls-imac kernel[0]: ** Device in slot: SLOT--1 **

    Oct  7 14:47:31 pauls-imac kernel[0]: ** GPU Debug Info Start **

    Oct  7 14:47:31 pauls-imac kernel[0]: 0x0000944a

    Oct  7 14:47:31 pauls-imac kernel[0]: 0x000000cd

    Oct  7 14:47:31 pauls-imac kernel[0]: 0x00000001



    Oct  7 14:47:53 pauls-imac kernel[0]: ** GPU Debug Info End **


    And, I can run Parallels VM's and all my other software with no issues.


    OK Apple, send me $100,000 AUD for fixing this!! Useless ********!





  • poluris82 Level 1 (10 points)

    Fellow amigos-in-distress, I finally left my iMac at the Apple store today. The person at the store said mine could be an issue with the graphics card (AMD Radeon HD 6970M, 1GB). He estimated $265.14 for parts and labor. He said I would not be charged if that doesn't fix the issue. He also noticed that my machine qualifies for a free replacement for the hard drive and offered to replace that too. For the long story, read on.


    My (mid-2011 27") iMac worked flawlessly for 13 months. Last month, just outside of the warranty, it suddenly started showing screen distortions and freezes when viewing youtube videos. But worked without a glitch other Flash-based videos. After a week or so, the issue happened at random during any activity. It would freeze with the screen showing a white (or white with black/gray stripes) layer over the entire viewing area. I could still hear any audio I was playing at the time of the freeze. After the initial trouble-shooting, I took it to the nearest Apple store (which was two hours away) and, funnily enough, the problem did not manifest for the 1-1.5 hours I was in the store. After that it worked without an issue for two weeks.


    Two days back, it showed the same symptoms and froze. This time, it started up with a greenish-tinted background, then the apple logo came on with the spinning wheel and then got stuck on the gray screen. Starting up in the safe mode did the same. Trying to get into recovery mode got stuck on a screen with blue background with black stripes. Extended AHT showed me the error code: 4MOT/4/40000003: HDD-1304. Reseating the RAM and other options did not seem to help. So, finally left it at Apple store today as mentioned above.


    I'll try to share what I find when the store calls me back in the next few days.

  • Johann P Level 1 (0 points)



    I think I just killed my GPU on my iMac. I was reflashing with RBE and when it restarted, my screen is just dead but my computer is still working. Is there a way to reflash the BIOS and reset it to default?

  • Lynn296 Level 1 (0 points)

    Hi Om_Audio,


    I had the very same problems you are experiencing with my Mid-2011 21.5" iMac. It started out freezing, screen going black, kernel panics. They tried erase and reinstall a few times and then replaced the graphics card. Worked fine for a couple days and then started freezing and going black again. I took it back in and got the same response, "We couldn't recreate the problem". The iMac also always passed their hardware diagnostics. Two times they suggested that it was environmental, but of course it was not. For about one week I kept a very detailed log, noting the time/date of every event, programs open, devices attached, and what I was specifically doing when the event occured. I typed it up and presented it at my next visit when luckily the screen went black on the genius bar counter. They replaced the RAM. After that, the computer was still freezing. I again kept a very detailed log for another week and took that back for another genius bar visit. (luckily I live near an Apple store). It took 2 hours at the genius bar. They were able to match my log entries up with the event and error logs on my computer. This convinced them to replace the logic board. It was interesting that I got a call from them saying my repair would take a few more days, something about the part in stock not being appropriate for this repair and a new part was on order... Finally my computer has been working perfectly for 2+ weeks. I also work freelance with Adobe software. My computer was out of warranty but I didn't pay for any of the repairs since I had a case number that started when the computer was under warranty.

  • Gandalf The Grey Level 2 (275 points)

    Lynn296: I had the same exact thing happen, started out with Lion being installed. Hard Drive they said was bad then a second hard drive and then memory and then the logicboard. After 4 times being in the shop, since I had Apple Care I asked for instore Credit, which they gave me back and I bought a Macbook Pro for my wife a Apple Display and a Mac Mini which is still going strong. Personally after seeing the new iMac's with the old side by side at the Apple Store and Best Buy I would never buy the older version as they put off so much heat it is so hot too the touch in comparisons to the new ones. The new iMac run cool, and I think heat is the major issue for these machines. I have had great luck with there products in the past and even now with the exception of my iMac, I will be ordering a new one eventually again the because new ones running all day barely putting out any heat, which I think is a conributing factor!  If you have Apple care and your machine has been in 3 times one can ask for a instore credit. I think a class action lawsuit is going to happen soon in regards to this issue. 

  • Om_Audio Level 1 (15 points)

    Not sure if it might help some folks but I have seen some relief in one case where there were tons of fonts. Went through and unregistered a ton and seems to have helped. Worth a try.


  • Lynn296 Level 1 (0 points)

    I'm hanging onto all my logs and history. And I'm continuing to log any events, even minor, since in the past the problems started fairly small and got progressively worse. My advice to anyone else dealing with this is to keep detailed logs and be sure to note the time/date of individual events. It was also important that I made it obvious that I was an experienced Apple computer user. They get a lot of customers that are not (one woman next to me wasn't able to figure out that she needed to simply change her email password, and didn't know how to do it!) I was also able to point out that I was using the very same software, documents, fonts, emails, etc. on my MacBook Pro with absolutely no issues.


    It's interesting, my computer used to put out more heat. Now it's a little warm but not hot like before.


    I'm glad my computer is working great now but I appreciate hearing about your experience. It confirms that I should continue to keep up my log just in case...

  • raidertodd Level 1 (0 points)

    Had similar problem with my iMac 24", not the 27" early 2009. I have had it in the shop twice, going back for my third time this weekend. It had been kinda comical. I always figure, the Apple Store tech's will know the machine and figure out the problem. WRONG! The first time I took it in, it froze for them, and they said immediately, it looks like the graphics card or the screen. But, they did nothing to either one. Instead they said, no, your hard drive failed in test right away, so they replaced that for a stiff price. It's out of warranty, started doing this a month after the warranty was up.


    Took it home and crash. Took it back. This time they said it was the logic board. Which was why my Disc drive was not working. (Forgot to mention that). I told them, you said it was the HD, now it's the logic board instead, how much will that cost. They took off the amount the charged me before, which was ok, but not great. New logic board, new hard drive. Now, it is running much better than it was, but, a day later after it came back, crash. Always video related, not gray or white lines, it just replicates the screen, or the you get pin ****** of red dots, or the whole thing starts flickering like poltergeist. And on top of that, 2 of my USB drives don't work now.


    So, I called Apple, told them what happened and to there credit, for once, they told me I would not be charged for any further repair as they had told me it was one thing, or two,  and it wasn't. The funny thing is, I have not been able to take it in yet, and it has only crashed maybe 2 or 3 times. I was crashing everyday, without fail. So, obviously the work they did has helped, but not completely. The point being, shouldn't they at Apple, know exactly what was wrong, why it's doing, what's it's doing. Read the crash reports and know what is failing and fix that. I feel like I am taking my car in to garage that is trying to make a buck without really fixing the problem. I mention the over heating and that re-balling the video card may be the solution,(I believe that's what it's called when you put down new solder) and at that point they shut up and became very politically correct. Well, Apple hasn't said anything about that, so we can't comment. lol Wow. I am very disappointed and think that I will get a Mac Pro next time, so I can replace my own parts thank you, without the Geniuses mucking it up. As far as I'm concerned, when you pay as much as we all did for a top of the line iMac, this should never be the case!

  • iDik Level 1 (0 points)

    In my experience, this particular error shows pretty much nothing on logs, other than the operators restart. Cooling is a keypoint in keeping the machine stable.


    It's odd that people get stability from different hardware switchout, some graphics cards, some logicboard. I found stability in my late 2009 27" i7 using smcfan, but it was getting super hot on the top.


    I now have a 2011 27" i7 3.4 and its solid stable, having not been turned off since I got it. It runs cooler, but I do have alot of beachballs, maybe OS or inadequate ram related. It has a better graphics card for sure. If I'd kept my 2009 I'd have tried upgrading to a better graphics card, not just replace it. Having owned a great deal of Apple prodects for home and work, the 2009 imac issue was my first frustration in many years iof use.

  • Lynn296 Level 1 (0 points)

    In my case it showed up in the error log. Here's what they noted on the Work Authorization:


    Steps to Reproduce: Console log error of "sleep failure code 0x00000000 0x31000000 correspond to the times customer is reporting either the system becoming unresponsive or the display blanking out altogether. Long dumps of kernel GPU Debug Info with memory addresses also appears.


    Proposed Resolution: As ram, video card and erase and install have all been performed: logic board repair with erase and install.