7 Replies Latest reply: Nov 17, 2012 10:59 PM by BDAqua
kahunah Level 1 Level 1 (0 points)

I have a 27"iMac that I am working on. When I turn it on, I first get a white background with 4 or 5 vertical stripes. If I leave it alone, it will eventually go to an all blue screen.


I was able to boot into safe mode. The screen looked fine. I had the OS X install CD in, so I decided to reinstall the OS. It said it would take about 55 minutes.


Then the screen got all kinds of wierd pixels in it, making it impossible to read. I turned it off by holding down the power button.


Now it seems the OS is gone, and did not complete reinstall. Holding down the shift key DOES NOT put me in safe mode. It seems to be attempting to continue with reinstall (I can hear the CD/DVD).


Now I just get a blank light-blue screen.


The vertical lines on the white background are persistent at startup.


Any ideas?

iMac, Mac OS X (10.5), I'm guessing at the OS version
  • BDAqua Level 10 Level 10 (120,940 points)

    Hello, let it cool down good & see if you can install & get these.


    Have you blown the dust out lately?


    Get Temperature Monitor to see if it's heat related...




    iStat Menus...




    And/or iStat Pro...



  • kahunah Level 1 Level 1 (0 points)

    It was doing the same thing (White background with about 5 vertical stripes) when cold (off for multiple days).
    Not sure if it is driver related or GPU problem.


    When I booted into safe mode (before attempting to reinstall OS), the screen looked fine. Colors were good, and no wierd pixels.


    I'm back to attempting to reinstall the OS. I get to the screen where I choose the language, but even on that screen I have lots of wierd pixels showing up (except on the on-focus dialogue box -it was clear until I made the choice to continue).



    I don't think this problem is heat related (due to the same screen when cool).



    I can't install any utilities until I get an OS back on it.

  • BDAqua Level 10 Level 10 (120,940 points)

    One way to test is to Safe Boot from the HD, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, Test for problem in Safe Mode...


    PS. Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive


    Reboot, test again.


    If it only does it in Regular Boot, then it could be some hardware problem like Video card, (Quartz is turned off in Safe Mode), or Airport, or some USB or Firewire device, or 3rd party add-on, Check System Preferences>Accounts>Login Items window to see if it or something relevant is listed.

  • kahunah Level 1 Level 1 (0 points)

    I'm still trying to reinstall the OS. The screen is heavily pixelated (for lack of a better term -it has artifacts all over it). I can still kind of make out "preparing installation" (see images) and the cursor is the rotating rainbow. --Been like that for about 2 hours.


    I don't think I can do much more until it finishes. I can't boot in safe mode until I have an OS installed on the hard drive to boot safely into. PB170019.JPG

  • BDAqua Level 10 Level 10 (120,940 points)

    It doesn't look like safe Mode will even work, not sure but I suspect the Install Disc uses the Safe Video drivers.


    Something is terribly wrong with you Video card it seems. Possible it's RAM though, especially if your iMac has Intel Graphics.

  • kahunah Level 1 Level 1 (0 points)

    I tried pulling the memory indivudually, no change.


    I ejected the install DVD and booted back up. I only get a folder with a flashing question mark.


    Are there any boot utilities that I could use to delete the partition on the hard drive? Then I could try to reinstall.


    Might be time to contact Apple. I don't know how old the computer is. (it's a clients) -I have heard something about Apple standing behind the video problems, but will have to verify.

  • BDAqua Level 10 Level 10 (120,940 points)

    If you don't know the model, find the Serial# & use it on one of these sites, but don't post the Serial# here...






    How to find the serial number of your Apple hardware product...