iMac G5 uncontrolled reboot

Discussion in 'Mac Basics and Help' started by DaveTheGrey, Aug 21, 2006.

  1. DaveTheGrey macrumors 6502a


    Dec 28, 2003
    Hi guys, perhaps one of you can help.
    I searched the web and several forums but didn't found a solution.

    First the specs:
    iMac G5, without iSight
    768MB of RAM
    10.4.7 with all available updates.

    This machine isn't used very often. In the maintime I controll it with Remote Desktop.

    It started with a "klack" during the boot process (after the grey screen during the blue one)
    after the klack the system stops. after a few minutes it starts again to read from the hd and then another "klack". this happens 5 times and takes about 10 minutes.

    right after that i rebooted the system but then there were fewer "klacks" until the system booted flawless. (took about 4 reboots)

    if i shutdown the iMac complete, the klack things starts again.

    if i don't shut down the imac and let it go to sleep, it automatically reboots every 15 Minutes. The whole day long. I don't know if that also happens when i would work with it but i don't think so.

    My unsuccessfull repair trys:

    - changed the hd
    - reinstalled the whole system
    - reinstalled the comboupdate
    - repaired permissions
    - repaired the drive
    - option+alt+p+r holding at startup

    I think this really sounds bad and is a tricky one, but perhaps one of you can help me... :(

  2. blodwyn macrumors 65816

    Jul 28, 2004
    Portland, Oregon
    By 'klack' I assume you mean an audible sound? If so this sounds like a hardware problem. Do you notice anything going weird on the screen when the klack happens? If so it could be a power supply or logic board issue. If it's the power supply then it may be covered by Apple's extended repair program for the G5 iMac PSU's. Probably the best thing to do is take it to an Apple store if you have one where you are in Germany and let a genius take a look.
  3. DaveTheGrey thread starter macrumors 6502a


    Dec 28, 2003
    Yes it's an audible sound.
    Nothing unusual on the screen before after or during the klack.
    No Apple Store in Germany. In Europe there is just one, which is located in London...
    Is there a chance to get this support from apple germany?

    Thanks for the Link and your time!

  4. DaveTheGrey thread starter macrumors 6502a


    Dec 28, 2003

    it seems sleep mode is the problem.
    instead of going to sleep the iMac restarts. Now I know why the restart period was 15 minutes.
    even when I trie to put the imac manually to sleep it restarts.
    but not like a normal restart. first it goes to sleep normally and in the next second the grey bootscreen appears.

    I think I've got to reinstall the whole os...


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