iMac shuts off immediately after powerup

Discussion in 'iMac' started by Aldyn, Jun 1, 2009.

  1. Aldyn macrumors member

    Jun 27, 2006

    Sometimes when I turn my iMac on, it'll start doing its thing—light comes on, chime goes, fan whirrs, but then it'll make a strange click/"werrrrh" noise and turn off.

    It's happened twice to me since I've brought it home from school and each time I just tilted the monitor around while turning it on and it worked.

    I have been avoiding turning off / restarting my computer because I'm afraid its going to happen and I won't be able to get past it.

    Could the powersupply be loose or something? I really have no idea!
  2. iLog.Genius macrumors 601


    Feb 24, 2009
    Toronto, Ontario
    Looks like PSU failure. If not that, then it would be the logic board but that seems unlikely. You will need to take it in to have it checked out and possibly replaced.
  3. drzz macrumors newbie

    Jul 14, 2011
    Sorry to resurrect a five year old thread but...

    Aldyn, did you ever find a solution to this problem? I have an iMac G5 exhibiting symptoms that are nearly identical to what you describe. If you found out what was wrong (or even better - a permanent solution) I would love to hear it.
  4. BEL86 macrumors newbie

    May 4, 2011

    I was having the same problem, and now it won't turn on AT ALL! I just bought it a month ago and I was so I'm nothing but annoyed and disappointed! Please help!
  5. Texran macrumors regular

    Mar 12, 2011
    Read here't_boot
  6. Tnthomson macrumors newbie

    Jan 11, 2013
    Hey guys, my iMac (from 2008) does the same thing... I recently got my RAM changed and since then when I switch it on, the apple logo appears with the loading circle and a loading bar. Please help!!!
  7. jaxhunter macrumors regular


    Dec 14, 2012
    I'm presuming that that is one of the original white plastic 24' iMacs... Those were known to have sketchy power supplies. The sysptoms you describe are dead on for the power supply beginning to fail. The good new is that those power supplie are relatively cheap and relatively easy to replace. That model should still be supported by Apple which means you should be able to take it to a nearby Apple Store and have it diagnosed and serviced.


    The iMac G5s had issues with both their power supplies and with bad capacitors on their logic boards. Could be either one. Unfortunately parts for those are hard to come by and expensive. You may be better off looking for a newer, possibly used iMac to take over.

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