Late 2009 iMac 27" Chime & Full Fans But No Boot

Discussion in 'iMac' started by cmcnj62, May 8, 2016.

  1. cmcnj62 macrumors newbie

    Jul 7, 2009
    Hey everyone,

    Long time reader, first time poster. I have a Late 2009 27" iMac (2.8GHz i7/Radeon HD4850) that chimes but won't go any farther than that.

    When you press the power button it will bong, the fans will ramp up to their highest setting and then nothing comes up on the screen but it doesn't seem like it's booting and just not displaying either. Tried a PRAM and SMC reset and while the computer did respond to those commands it didn't change anything. Also tried swapping the RAM but made no difference. I'm not getting any lights on the keyboard either. Any ideas?
  2. iSee macrumors 68040


    Oct 25, 2004
    This is almost certainly a hardware problem.

    I think you would have to open it up and take a look. If you're lucky, you'll find a loose or separated connector. Or perhaps you'll be able to spot fixable physical damage.

    Of course, you can alsontake it to a repair shop.
  3. cmcnj62 thread starter macrumors newbie

    Jul 7, 2009
    Found the solution!

    For anyone with a similar problem, check the diagnostic LEDs on the underside of your computer - they are visible through the speaker grill. I noticed diagnostic LED #3 was not on when the computer started which indicated that the iMac was not communicating with the graphics card and upon further investigation and after a few reflowing methods I determined the ATI Radeon 4850 that came with the computer was completely dead. I then ordered an ATI Radeon 5670 off of eBay, swapped it out and BAM - back to working like a charm.

    Hope this helps someone else out there with a similar puzzling issue.

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