Early 2008 Imac 24" black screen?

Discussion in 'iMac' started by NeoCool, Jan 24, 2013.

  1. macrumors member

    Jan 6, 2011
    Early 2008 Imac 24" black screen?
    Hi all, could I get some feedback.
    My early 2008 Imac 2004 is now not displaying anything.
    It has the normal startup sounds, fans, chime. but nothing on display.
    Also tried a external display adaptor but nothing comes up on external.

    would love some constructive feedback please.
  2. macrumors 603


    First thing to do is to shine a light on the display with a torch, if you see there is the normal OS X GUI you know it's the backlight but I think there is something else going on here since an external display also does not work.

    If this is the case then most likely the GPU is faulty.

    You might have the nVidea 8800, if that's the case you might have a known defect.

    NVIDIA 8800GS Failure Rate
  3. thread starter macrumors member

    Jan 6, 2011
    HI Thanks for quick reply.
    I can confirm nothing when light shined on screen.

    read linked thread and seems a common problem.
    sounds expensive the NVIDIA 8800GS

    Did apple do a recal and free replacement on this even though its now out of warrantee?
  4. macrumors 603


    Check out https://selfsolve.apple.com/agreementWarrantyDynamic.do

    But, it's already old, don't think you'll be able to replace it free of charge, and Logic boards are expensive, not only that, it will get into the same problems later on.

    But, you really need to check if you have the 8800GS, they came with two different GPU's.

    Graphics Card ATI Radeon HD 2600 PRO or NVIDIA GeForce 8800 GS
  5. thread starter macrumors member

    Jan 6, 2011
    Ok got lcd out and can see the logic board, power supply, hard drive, optical drive, blutooth, sound,

    but no sign of GPU is it behind the logic board?

    Ill have a look then to see what model it is.

  6. macrumors 603


    You can see on iFixit.com how to disassemble the iMac, choose guides and enter your model.

    It's almost sure to be on the Logic board, you can not remove it, it's unlike most Desktops which come with removable GPU's.

  7. thread starter macrumors member

    Jan 6, 2011
    cheers i see it know its a nvidia.

    many thanks for your help.

    Ill try and source a reasonably price one. lol.
  8. macrumors member

    Nov 11, 2011
    My 8800 burned out last year but it turned out that it was actually a motherboard issue rather than the card itself (the board shorted the card so both needed to be replaced), I had to go through Apple to find the card, it's a very difficult card to find aftermarket, but because it happened within a month or so of my AppleCare expiring they fixed it for free :).

    Another thing to check is the PRAM Battery, it need to be replaced every 5 years or so and it powers stored information on screen resolution and calibration (among other things) which could cause you to get a black screen when it fails. Replace this battery before you commit to buying a new card and see if it makes a difference, it's a long shot but you'll have to replace it eventually anyway so it's worth trying.

    Good luck.
  9. thread starter macrumors member

    Jan 6, 2011
    Will It happen again?

    Hi thanks for support on the 2008 iMac with gnu failure.

    Are we saying here that the design fault causes the gpu to overheat and fail.

    So if i replaced it with another it would most likely go the same way.?

    just checking as if that is the case it may be worth me investing the monies in a diff Mac.

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