To those having random shutdowns on Alu iMacs

Discussion in 'iMac' started by resonance, Feb 16, 2008.


If you have had random shutdowns, do you have an external hard drive connected?

  1. Yes

  2. No

  1. resonance macrumors newbie

    Dec 6, 2004
    I think I may be getting somewhere with the problems I have been having with my 20 inch Alu iMac. Occasionally, It will shut down completely (as in turning off), and sometimes it will refuse to wake from sleep. Often after these occurrences, pushing the start button to reboot the system will cause the machine to 'whir up' but will never get as far as the 'chime'.

    I have now realised that if my external hard drives are UNPLUGGED I have none of these issues.

    I have a 250Gb Western Digital MyBook and a 500Gb Seagate

    Any further thoughts Alu iMac owners?:confused:
  2. Mac Addict macrumors member

    Mac Addict

    Feb 12, 2008
    Sorry to hear about your issue. My setup is near yours, and I have never had any hiccup with shutdowns or waking from sleep.

    I have a 24" Alu 2.4C2D w/ a 250gb my book for Time Machine. The iMac is set for sleep after 30min & I never power off unless Im leaving town for business.

    Have to ask, assume you are using firewire 800 port?
  3. resonance thread starter macrumors newbie

    Dec 6, 2004
    To be honest I have only ever heard of these faults on the 20 inch models. I use the hard disks on regular usb 2.0 thats 800 right?
  4. Mac Addict macrumors member

    Mac Addict

    Feb 12, 2008
    Note the exact time when this anomaly happens, then check your:

    Applications --> Utilities --> Console --> System Logs

    It should tell you what's acting up. Post back what you find. Good luck.
  5. resonance thread starter macrumors newbie

    Dec 6, 2004
    System log only seems to tell me about as far back as the reboot after crashing. This time it turned off in Windows (never happened before, not that I use windows much).

    The log simply tells me start up routines etc rather than anything about the 'crash'

    I'm worried its not a software crash at all, or even over heating (i hear they force sleep in that instance), and that it could be the hardware. is it worth trying to replace the power cord? Will other 3 pin connecters like it work?

    The fact that it happened in Windows tells me it must be firmware or hardware.

    oh and guess what - I had no hard drive attached!!:mad::mad:
  6. Applespider macrumors G4


    Jan 20, 2004
    looking through rose-tinted spectacles...
    No. USB 2.0 is USB
    The 800 is the Firewire 800 port. I'm guessing you're not using it.

    Do you have any third party RAM in it? If so, can you remove it and run with the default RAM for a bit and see if the same problems happen?

    Restarts/freezes are common signs of slightly dodgy RAM
  7. rworne macrumors 6502a

    Jul 23, 2002
    A sudden abrupt shutoff is also a sign of a thermal issue. It would not hurt to load up one of the temperature/system monitoring programs and see what the temps are for various components.

    Another possible culprit is the power suppy voltage. Some of those programs also will monitor what the computer sees for voltages too.
  8. jaredisme macrumors newbie

    Feb 17, 2008
    The computer is probably trying to boot from the external hard drive and thats why it wont start up but I'm not sure why it would shut down like that.
  9. resonance thread starter macrumors newbie

    Dec 6, 2004
    I did wonder if it was a power problem. I checked teh console after my latest crash and it simply stopped writing to it, halfway through a word, so there is literally no software telling it to shut down.

    I took a screenshot of my temps - it crashed about 5mins ago. :mad:


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