iMac freezes on white screen, gear stops spinning

Discussion in 'iMac' started by synthetic hero, Aug 14, 2012.

  1. synthetic hero macrumors newbie

    Joined:
    Aug 14, 2012
    #1
    My 2008 24" iMac has stopped booting up all the way. When I hit the power button I do get the chimes that play, and I get to the white screen with the grey apple, however after a few seconds the gear stops spinning.

    Here's what I've tried so far:

    1. Holding down Shift while booting: get progress bar, but gear eventually stops booting
    2. Holding down Option: I get Mac HD, Recovery HD, and Install Disk. Choosing any of them gets me back to white screen, and gear stops spinning.
    3. Holding down Command + Option + P + R: Causes reboot, boot after that gets me to white screen, gear stops spinning.
    4. Holding down C to boot directly to install disk: Same result, gear stops spinning after awhile.
    5. Leaving iMac unplugged for a few hours. Same result.

    I'm pretty desperate at this point. I'm looking for any ideas.
     
  2. 666sheep macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #2
    It seems you have more serious problem and you need to troubleshoot hardware starting from RAM (easiest) and SMC reset.
    Did you notice any strange behavior recently? Graphics glitches, slowdown or freezes?
    Your iMac has 8800GS? If so, it could be a culprit. Those were dying frequently.
     
  3. synthetic hero thread starter macrumors newbie

    Joined:
    Aug 14, 2012
    #3
    I've had no graphics issues at all lately. No unexpected slowdowns.

    I'm pretty sure it's hardware. The mac was on when our power flickered. It turned off, but wouldn't turn back on all the way. The first time it booted to the login screen, which went to screen saver and froze. Now any time I try to boot it I get this issue.

    I'll try the SMC reset, although I thought that would have been covered by leaving it unplugged for a few hours.

    As far as the RAM, I have two 2GB modules in the bottom of it. I've tried booting it with only one or the other in place (with same results), but i haven't tried swapping the slots or anything.
     
  4. 666sheep macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #4
    If it occured after power failure, you have basically 2 possibilities: PSU and logic board. It'll be rather hard to test both of them without working spare ones. You could try to obtain Apple Service Diagnostics 3S123 - this is right one for you iMac revision -> search the web. If you'd manage to boot of it somehow run full test.
    If you're savvy enough to disassembly your iMac, you could inspect logic board and PSU looking for physical damages (burnt SMD components or bad caps).

    Alternative is nearest ASP or genius bar.
     

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