Previous 1 2 3 Next 115 Replies Latest reply: Oct 9, 2010 9:42 AM by Dave13
TheNewFlesh Level 1 (0 points)
Hey everyone.

Recently, my white iMac has been locking up a lot lately (forcing me to hard-reset, boo) and horizontal lines have been appearing. It freezes most often during more graphically-intense applications like games and Pro Tools. It's not the regular Mac freeze, where the grey dialogue box politely and multi-ligual-ly informs you that you need to reset. When my computer freezes, things just lock up, or the screen will go black.

I thought since I had not done a whole lot of computer maintenance since I bought it, there was a possibility it was just a horrible software glitch.

So I zero'd my hard drive and reformatted. Almost immediately the lines returned. Interestingly enough, I don't need a digital camera because these awful lines can get captured by screenshots.

The lines are typically pinkish or black, but if you look close, the individual pixels in the lines seem to be coloured arbitrarily. If the lines appear on a window, I can drag it around and the lines will follow. If I resize the window, the lines disappear.

Here's a screenshot. Note how the lines only affect the one window, and do not span the entire screen.

These lines aren't bound to a particular window, just the desktop as a whole.

How are these things getting captured on screenshot if I just reformatted my computer?
If it's not a software error, could a worn-out graphics card produce odd artifacts that are screen-capture-able? Apple ships hardware that can't last 2 years? Am I going to get shafted if I try to call them? Is there possibly a fix for this?

Thank you everyone for taking the time to read my post, and thanks in advance if you have some advice or want to express that you share the same issues.

2Ghz Intel Core Duo 20" White iMac, Mac OS X (10.4.9)
  • Addict Level 1 (0 points)
    I'm having the same problem. I'm going to go into the apple store and see what they can do. My warranty is up in 5 days. I think I might be buying applecare, which ***** to have to do.
  • Satoru Murata Level 1 (15 points)
    Are you getting these lines under Tiger, as your system info signature suggests?

    I ask because I'm pretty certain this is a software/driver issue, and just to make sure, I booted back into Tiger loaded on an external drive and the lines pretty much go away. I boot back into Leopard and the lines and other graphical glitches abound.

    In a way, that's a good thing because it means Apple can potentially fix it with the upcoming 10.5.2 update. I have my fingers crossed.
  • Scott Feld Level 1 (0 points)
    I'm having the exact same thing, I had screen errors on 10.4.10 and hoped an upgrade to Leopard would clear it up.

    I'm glad to see it's not just me. I also get the blank screen lockup and the active screen lockup- as well as the "polite" apple gray box telling me to restart the computer.

    I can see the distortions and lines through screen sharing, so I would think it has to be software related. I also get distortions like a section of the screen is "warped" in 3D.

    Here's my pics, sorry about all the fuzziness, it happened to be my email and don't want to post family and friend's email addresses.

    Hope there's a fix!

  • ChrisEdgington Level 1 (0 points)
    I'm having the exact same problems on my MacBook Pro. Has anyone found a solution? I don't want to take it to Apple for repair unless I know the repair is going to solve the problem.

  • RobAnybody Level 1 (0 points)
    I started getting horizontal stripes about a month ago. I've chased down lots of potential leads from memory issues to bad software. As of now I'm thinking that the problem is heat related, specifically when running graphics intensive software.

    One of the worst offenders seems to be firefox. I can see the temperature starting to go up on the istat pro widget when I am running firefox. Safari seems to cause less heat to be generated, although it is not immune from the stripes or even patches of color or improperly redrawn parts of a window. As the heat increases, the problems do as well until it finally locks up.

    I really started to worry when the gray screen of death started to happen almost every day, often not allowing me to turn the system back on for hours, or even overnight. For whatever reason, unplugging and reinserting the power cord seems to allow it to come back on without waiting, although this just might be superstition on my part.

    For now I am nursing my system along, watching the temperature and closing down any programs that I don't need. I have had some success by changing the sleep settings for the computer to 30 minutes of inactivity and 15 minutes for the display.

    I know its going to have to go into the shop soon, but I am trying to hold out as long as reasonably possible since it is a work machine for me.
  • John Williams9 Level 1 (0 points)
    Hello all,

    I am having the same issues as well on my 24". It was doing it under Tiger, but not as much, and now under Leopard, but it doesn't seem to be the operating system since I have reformatted several times thinking it was. I have reset the PRAM and also followed the directions shutting down, unplugging everthing, and restarting with the power button held down but nothing changes. Doesn't seem to be any particular software that starts it.

    I will monitor the heat and see if that is high. I usually leave my computer on all night too as I back up then, but I will start shutting it down and see. My warranty expired on January 8th 2008. Hmm.
  • scoobeepsk Level 1 (0 points)
    I have the same issue. My started when I loaded the 10.5.2 update along with the graphics update. I turned off genie effect and that seemed to help. I was going to reformat today, but after reading John's post, decided not too.
  • RobAnybody Level 1 (0 points)
    As I suspected, heat is the culprit for me. I saw the donationware program smcfanctrol2 recommended for a similar issue. I am using it now and it is working very well.

    By bringing up the cpu fan speed I was able to watch the temperature come down (using the istat pro widget) and problems with the lines almost completely went away. I haven't had a crash with it and I can now run videos and firefox and all my graphics intensive software without much problem.

    Also, don't forget to blow or vacuum the dust out as a first step towards reducing the heat.
  • John Williams9 Level 1 (0 points)
    Since my last post, I have not had any more problems! I guess posting here magically solves all issues I have no idea why I am not having these problems any longer, but I am sure they will return!

  • scoobeepsk Level 1 (0 points)
    Well I had an appointment to take my imac in, but saw your post and wanted to give it a shot. I redid my computer and loaded the smcfancontrol. I am not sure what settings to use, but your right...I have only had 2 lockups since. No lines...and you might say 2 lockups is still bad...well no, not compared to before, and I was really taxing my system...(example: converting a movie from apple tv to iphone, running xp, copying files from my portal drive back to my system all at the same time. So far so good. the line issue has to be heat related, because I have only seen it once since my re-due. I will post here in a week with an update. By then, I am sure I will be either really happy or will be taking my system in for repair.
  • RobAnybody Level 1 (0 points)
    I've tried different settings on smcfancontrol but finally settled on 2350 for the CPU, 2000 for the ODD and 2650 for the HDD. Maybe I've got the fans running too fast, but all I know is my GPU Diode is running 30-35 degrees (F) cooler than it was when it would crash, even with Firefox running, and I don't have any more lines or artifacts.
  • scoobeepsk Level 1 (0 points)
    yeah..i was a little worried about turning them up too fast..But I think the 2 lockups I had, my temp got up to 126 f, so I might increase it closer to your specs.

  • cyul Level 1 (0 points)
    Just to add a few comments to this thread, I had similar problems (green dots appearing at random locations on the display, lines, then corrupted icons graphics / text, and eventually computer lock-ups that required a power/hard reset).

    It took me weeks to realize that heat was the root cause of these display artifacts / computer lock-ups. I had run zillions of memory tests, ran the Apple Diagnostic so many times, tried TechTool Pro, and I never ever got reported with a single error by any of these tools. I swapped RAM, disconnected all external Firewire / USB devices, tried different versions of Tiger / Leopard, to eventually conclude it had to be something else...

    ... and then it struck me one evening this week. I realized that I was now using my Mac Mini to transcode video (a task that I used to perform with my iMac, but that I stopped to use as a transcoding device as this would eventually lead to the symptoms described above), and that the Mac Mini's fan would increase in speed when the CPU would get loaded. It is then that I realized that I had never heard my iMac's fan change in pitch... with the exception of when I was running the Apple Diagnostic tool !!!

    Gotcha !

    I also downloaded the latest version of smcFanControl, and changing the fan settings to 1200 (ODD), 2200 (HDD), 2000 (CPU) fixed all the symptoms.

    I submitted a bug report to Apple about this, as I consider this is a major issue. I have seen the temperature of the power supply reach 80+ Celsius. Water boils at 100 Celsius. That is hot, way too hot.

    I hope Apple will fix this issue ASAP through a SMC firmware update as fans control is meant to be automated.

    Just my 0.02$CAD.
  • mahycl Level 1 (0 points)
    Hello everyone - I was having the same issues. As shown below in the first set of links:

    I downloaded and installed the smccontrol program as others have done and in a matter of 5 minutes it had decreased the temperatures significantly, and I'm already used to the different fan speed noise. See following pictures for before, 3 and 5 minute intervals screen shots.

    Thanks everyone - hopefully this will help with the freezing and the artifacts that I've been getting more and more of. I'll vaccuum the ports off when I won't be waking up my wife (see time on screen shots)
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