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iMac Freezing

122535 Views 562 Replies Latest reply: Aug 31, 2009 6:08 AM by Zachnap RSS
  • robertleeking Calculating status...
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    Aug 30, 2009 10:07 PM (in response to Micah D.)
    Micah,

    As I said, your problem is hardware. From the description of others, they may not share the same problem even though the circumstances seem similar. I'm not beating anything here. You simply failed to understand what I said.
    iMac 24" 3ghz, 4gigs RAM, 1terabyte HD, Mac OS X (10.6), Mac SE30, Clone PC win2k, Toshiba Laptop Vista Home Premium
  • robertleeking Level 1 Level 1 (35 points)
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    Aug 30, 2009 10:25 PM (in response to Digler)
    Digler,

    You may have a failing GPU but, considering it didn't do it in safe mode, it's hard to say. Frankly, I would not personally put up with the failure you mention for a day much less a few months.

    Have you run the Hardware Diagnostics Application CD? If so, does it find any issues?

    Does your system freeze during the full diagnostics?
    Does your display operate correctly while running the full diagnostics?

    If so, you have not elliminated software as a possible cause. In either case, by all means spend the money on a new GPU. It might fix the problem, then it's money well spent but if it doesn't?
    iMac 24" 3ghz, 4gigs RAM, 1terabyte HD, Mac OS X (10.6), Mac SE30, Clone PC win2k, Toshiba Laptop Vista Home Premium
  • milankovach Calculating status...
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    Aug 31, 2009 12:43 AM (in response to Alley_Cat)
    To me this implies that the GPU hasn't crashed, but that the part of the display driver which updates the GUI has crashed - perhaps in response to an error from the GPU, but if the driver can still update the cursor, then clearly the GPU is responding.


    video ram is failing for sure (those horizontal lines of random pixels are there because video ram is also fried).

    as eastfirst169 say it is very possible that vram chips didn't have proper cooling! (this is not first time - I saw meny PC graphics card that have heat-sink 1-2mm above vram chips without touching it (or there is a lot of thermal tape)!

    Bob and several others may not be experiencing the same thing as you and as such, in their cases it may not be a hardware issue at all. Rule out software first, then move on to hardware.


    @robertleeking it is hardware issue - because GPU made errors (you can see in logs files, just read this thread from start, somebody already post it) and because of this errors from GPU whole UI freez - but only UI part of OS, you can still access iMac via network, music continue to play...! so only UI part of software crash due error from GPU.

    Generally once an issue is known, it falls to specific serial number ranges. For example, with the Powermac G5 line, there were known power supply problems in specific production runs. Apple replaced those power supplies for quite a while after those machines were no longer under any kind of warranty.


    we want the same for our white iMacs 2006.!

    You may have a failing GPU but, considering it didn't do it in safe mode, it's hard to say. Frankly, I would not personally put up with the failure you mention for a day much less a few months.


    it did not do it (freez) in safe mode because QUARTZ EXTREME IS TURNED OFF in safe mode!!

    "Safe Mode in Mac OS X 10.5 or later also disables Quartz Extreme (hardware accelerated graphics). Applications that depend on Quartz Extreme will not open..."
    http://support.apple.com/kb/HT1564

    Have you run the Hardware Diagnostics Application CD? If so, does it find any issues?


    if you read thread from beginning than you should know that many, many people (or Apple technicians) try Diagnostics app and it did not find any errors any time!

    Message was edited by: milankovach
    iMac C2D 2.16GHz white - freezing 5 times every day! :(, Mac OS X (10.5.7)
  • MarekSz Calculating status...
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    Aug 31, 2009 1:13 AM (in response to milankovach)
    Milan,
    I can only add that: even test with Apple internal service diagnostic program shows no errors.
    iBook G3 800 (brick), iMac C2D 20 late 2006 (GPU failed) http://skocz.pl/danbf, Mac OS X (10.4.11)
  • Alley_Cat Level 6 Level 6 (16,630 points)
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    Aug 31, 2009 1:50 AM (in response to milankovach)
    milankovach wrote:
    To me this implies that the GPU hasn't crashed, but that the part of the display driver which updates the GUI has crashed - perhaps in response to an error from the GPU, but if the driver can still update the cursor, then clearly the GPU is responding.


    video ram is failing for sure (those horizontal lines of random pixels are there because video ram is also fried).

    as eastfirst169 say it is very possible that vram chips didn't have proper cooling! (this is not first time - I saw meny PC graphics card that have heat-sink 1-2mm above vram chips without touching it (or there is a lot of thermal tape)!


    I agree entirely with all those who say the underlying problem is hardware.

    No amount of software changes are going to cure the random lines/pixels etc.

    The freeze is a symptom of the hardware instability, and as you say probably fried VRAM - however the GPU may not have hung completely, but a timeout or incorrect response on a particular operation related to GUI updating may cause that thread/process to terminate unexpectedly or hang.

    The question is whether or not that hang is recoverable or not - it might be possible for the driver to handle it more gracefully and pop an error box advising shutdown because of an underlying hardware issue. This would not cure the issue but would at least allow you to interact to close things down nicely.

    Again it would not cure the issue and graphical corruption would still be apparent, but it might allow you to continue to use the machine in an albeit compromised state visually. The error may of course be quite unrecoverable without a hardware reboot to reset the faulty GPU.

    Realistically I see no prospect of a rewrite of the driver even if it were possible as it would be argued that an underlying hardware fault is an underlying hardware fault and that's the problem that needs to be addressed.

    Message was edited by: Alley_Cat
    3.0 GHz 8-core 14GB RAM, Mac OS X (10.5.7), Macbook, Mac Mini, Unstable/Unreilable iMac 20" Core 2 Duo
  • Zachnap Calculating status...
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    Aug 31, 2009 6:05 AM (in response to robertleeking)
    Getting Apple to "admit" this is a hardware problem generally requires a much larger sampling of the user community experiencing the problem. Based on the posts here, and the meager sampling found via Google searches, that sampling does not exist. This doesn't mean Apple won't do something about it only that it will take a lot more than a relative few complaints in various forums to cause Apple to act.


    Well, I don't know where you looked for your sampling information but I have a list of about 10 different threads and blog-posts about this issue. Are 200 or 300 or 400 complaints on-line relatively few? Look at our thread and compare that with the 4850 HD GPU issue with the newer iMacs - our thread trounces it and everyone who had that GPU had an issue. According to your logic there should have been thousands upon thousands of complaints about the issue, but guess what? There weren't, there were only a few hundred, yet the problem affected tens of thousands. Also, these failures took some time to appear and do so gradually which is quite unlike the 4850 driver problem which occurred so close to purchase, happened immediately and all at the same time. How many people actually post about a problem 2 years after a machine purchase anyway? Our problem appears to the average person to be just 'a bad video card' - they probably justify it to themselves: "I guess I was just one of the unfortunate souls who got a bad component through unluck-of-the-draw; next time I know to purchase Applecare." This is why you aren't seeing much coverage anywhere.

    Clearly, there is a problem. The question is, is it Apple's problem, the GPU maker's problem or something else.


    Well, it isn't the GPU maker because it is happening to 4 different video cards - probably the logic board is over-loading the GPUs and causing them to go bad - maybe a "leak" somewhere, maybe Apple used a batch of defective contact grease or maybe their was a bad Firmware update that set something into motion on the hardware side (e.g. I remember that when I first got my machine, I would occasionally hear the fan kick-on for a minute, but then I never heard it for months to a year - this could have started it all) - who knows.

    As I said, your problem is hardware. From the description of others, they may not share the same problem even though the circumstances seem similar. I'm not beating anything here. You simply failed to understand what I said.


    No. we all have the same issues, we have beaten this to death. Our iMacs have heat tolerance problems - that is why ALL of our computers graphical-freeze at 50 C or so; that is why we ALL get horizontal lines at those temps; that is why we ALL are upping fan-speeds to keep our iMacs below their sub-par temperature thresh-hold. How could we all have the exact same symptoms with the exact same models and "remedy" them with the exact same methods and then not be experiencing the same problem?

    I'd imagine that Apple has a reason for ignoring the issue. How costly would it be to replace every Late2006/Early2007 iMac? Hmm? How many were sold? 100,000? multiply that by $1000 (estimated system cost for Apple) - that is $100,000,000.00 They would have to issue a recall because many of the replacement components have already been used up and according to some, they end up failing as well.
    iMac 20" (Late 2006), Mac OS X (10.4.11)
  • al_broccoli Level 1 Level 1 (5 points)
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    Aug 31, 2009 6:03 AM (in response to Alley_Cat)
    I think people here are making assumptions as to what "the" problem is without first verifying that they're talking the same situations - same cards - same symptoms, etc.

    For me, I'm using an Nvidia 7300GT/7600GT in a late 2006 24" iMac, and the errors I'm getting are OpenGL errors in the system log (NVDA(OpenGL): Channel exception! status = 0xffff info32 = 0x3 = Fifo: Unknown Method Error). These problems can be recreated with a brand new card with the machine cold. So it is most certainly not +CAUSED BY+ heat, although it may well be exacerbated by heat.

    Is it software? Some have reported errors under Mac OS, and other graphics-related errors under Windows, so that would indicate it's not software. If those errors are the same errors, that is, and I'm not sure of that.

    Is it hardware? Some have reported this specific error even after replacing both the logic board and graphics card.

    Assuming both of these points are true (and that is an assumption at this point), that would lead me to believe the problem is in the Nvidia ROM. But I don't have definitive evidence to support that supposition.
    24" iMac Intel, Dual G5 Power Mac, 2 PowerBook G4s, Mac OS X (10.5.7)
  • Zachnap Level 1 Level 1 (10 points)
    Currently Being Moderated
    Aug 31, 2009 6:08 AM (in response to al_broccoli)
    Al, Do you run a fan-control program to keep your machine cool? Does your system freeze when the temperature gets to about 50C? If not then you are posting in the wrong thread.
    iMac 20" (Late 2006), Mac OS X (10.4.11)
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