iMac G5 - Black screen and loud fan noise upon boot

Discussion in 'PowerPC Macs' started by StuartCH, Feb 6, 2011.

  1. macrumors member

    May 28, 2008
    Sunderland, UK
    Right here it goes, my iMac's had this problem for a while now where if you were to turn it off for the night and you came back to turn it on it would stick to a blank screen, no disc noise and some loud fan whirring after a few minutes, but if I were to wait half an hour and reboot it, it would boot normally and go straight into Leopard. It never really bothered me before, but now this is getting beyond a joke since I'm selling it soon to get a MacBook and I want to solve this problem once and for all. Anyone mind helping me here?
  2. MacHamster68, Feb 6, 2011
    Last edited: Feb 6, 2011

    macrumors 68040


    Sep 17, 2009
    sounds like a soon failing harddrive if there are no other abnormalities , but on a g5 its always worth to check the capacitors anyway and to change the harddrive you have to open the iMac anyway , a good time to clean it inside too, but just another question i guess you did pram reset, permissions repair already or? and does it still remember the date and time?as of the age its due for a new pram battery too
  3. macrumors member

    Nov 9, 2009
    Which G5 is causing the problems, the 1.8 GHz or the isight? The 1.8 is much more susceptible to the bad caps issue (and also a bad power supply issue), so it's worthing inspection the logic board.

    MacHam's suggestions are all good ones. The only thing I'd advise is to check the RAM as well. I was having problems that were mis-diagnosed as a failing logic board (an Apple genius and a 3rd-party tech both got it wrong). Turned out it was bad 3rd party RAM. I put the original Apple RAM in the machine and the problems went away. Sent the RAM back to the manufacturer, got a new kit, and it's been running fine since. The symptoms I was having are similar to the ones you describe. Might be worth checking out if you have other RAM you can swap in.
  4. macrumors 601


    Sep 16, 2007
    Northeastern Ohio
    I think the failing to wake up from sleep with a black screen is PSU related or the infamous bad cap issue. If you are good at soldering, the cap kit can be purchased for less than $20.

    Have you ever noticed any lines on the screen or weird artifacts showing up? The other known issue with the G5 iMacs are the graphics cards. This requires re-flowing the solder or buying a entire new logic board.

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