8 Replies Latest reply: Jul 1, 2008 10:27 AM by nintendew
Derek Collier Level 1 (0 points)
i get bars of pixels going across my screen most of the time. They are sometimes black and other times they are multi-colored. Also when i scroll down a page, some times it does this funky thing where it looks like....man i cant really describe it..... i cant get a screen capture of it because it goes away when i click outside of the window
Also, if they are in a window, they will move with that window.
Could this be happening because of the video card going out?

The lines look just like this: http://farm4.static.flickr.com/3243/25990075431695b18555b.jpg

Message was edited by: Derek Collier

20'' iMac 2GHz Intel, Mac OS X (10.4.6), ATI Radeon X1600
  • nintendew Level 1 (15 points)
    I get those glitches also. People have been complaining about these things for a while now. I've been hoping for a Leopard update that would fix it, but I'm thinking about contacting Apple already. This is unacceptable even if I'm without AppleCare.
  • GLiMAC Level 1 (0 points)
    See this thread:


    I had the exact same problem. Seems to be caused by overheating. Download and install iStat Pro to monitor your temps, then download and install smcFanControl and set your fans to 2000RPM minimum. you should see a marked improvement.

    If your Mac is still under warranty, send it in for a fix, as it shouldn't be overheating in the first place. If it's not under warranty, you're looking at an $800+ logic board replacement, so get the software fix and go easy.

  • nintendew Level 1 (15 points)
    Hi GLiMAC. Yes, this does work, but I doubt this fix is good in the long term. I'm still hoping Apple would send some firmware updates our way because I can't even downgrade them to their original factory configuration.

    When did you first observe the glitches? I find it very suspicious that all my problems came shortly after the 10.5.2 update.
  • GLiMAC Level 1 (0 points)

    Actually I noticed it first on the upgrade screen from Tiger to Leopard, and it then became progressively worse, even before 10.5.2.

    Since increasing fan speed seems to help I don't believe it's a software issue, although software can play a part in stressing (or de-stressing) the video card. If the fans work for you and your iMac is out of warranty you might just have to live with it. The cost of repair for a video card/logic board (from what I'm told) is not worth contemplating.

    Also, as a photographer I'm not planning to upgrade to the new iMac because of the gloss screen. With any luck the next generation of iMac will have a choice between gloss and matte.


    Message was edited by: GLiMAC
  • nintendew Level 1 (15 points)
    I have my fingers crossed that it's just a firmware issue. I think the aluminum ones had the same problems before they were patched.

    So I'm just leaving my iMac alone in the corner for now. I don't want to do any more damage to it. It's clearly incapable of doing heavy computations and simulations with OpenGL.
  • RonsMac Level 1 (15 points)
    I installed the smcFan and it has helped. I had it set at about 25% and while gaming last night only once did my screen go black inside the game frame. Will increase the 3 settings to around 2k as mentioned above and see if that is better.
    I think it's time to do a full reinstall and start from scratch. I think that after almost 2 years the whole thing is working a bit harder than is should have to.
    Thanks for he help.
  • Crystal Smelser Level 1 (0 points)
    The video card on my iMAC G5 had to be replaced but what I experienced looked like my computer had a virus. My screens only on the MAC side not the Microsoft side would be garbled and hard to see. And when you opened a new window part of it was scrambled and by rolling the mouse over the scrambled parts it would unscramble the picture. Needless to say my brand new iMac had a bad Video card!! Your snapshot looks similar to what I experienced except it was a lot worse and it was bigger chunks of my screen.
  • nintendew Level 1 (15 points)
    I doubt a clean installation will help. But before the installer restarts machine, you might want to increase the fan speeds some more because of all the activity that will happen with the hard drive and the optical drive.