Is my iMac Dead?

Discussion in 'iMac' started by nanosour, Jun 8, 2016.

  1. nanosour macrumors member

    Joined:
    Dec 14, 2009
    #1
    I have the original Late-2009 27" i7 iMac which has served me well over these last 6+ years. Lately it has started to act up with random black screens that I had to hard shutdown to get out of. That has led to getting hung on boot up and the iMac will now only boot in safe mode.

    The iMac is running 10.8.5 and I have a TimeMachine backup. Here are the steps I've tried to get the computer to do a normal boot:

    1. Reset PRAM & SMC
    2. Created a bootable Mt Lion USB (will not load using Option key at start up, same hung state)
    3. Tried to get into Recovery Disk with CMD-R (hangs at the same point)
    4. Upgraded to El Capitan from Safe Boot mode (same results, i.e. will only boot in safe mode)
    5. Installed clean Mt Lion on external HD and attempted to boot from it (same result)
    6. Removed the internal HDD and tried to boot from USB (same result)

    None of these allowed the normal boot cycle to get past the white screen with the grey apple. It gets past the spinning lines then just hangs there indefinitely.

    At first I thought it was a failing HDD, but the SMART is "Verified" and Verify Disk says it is good. Now I suspect that it is either the logic board itself or possibly the graphics card. Radeon 4850 512MB VRAM model. I did take a screen shot from safe mode and the picture file is fine so my understanding is the graphics card is OK. Didn't have any weird screen effects other that the occasional black screen over the past few months leading up to this.

    Seems there is a kernel panic happening and I did check the diagnostic logs in Console, but could not identify anything specific. Given that this is happening to a clean install on an external HDD, I'm assuming it is not some third party software that is causing this behavior.

    Can this iMac be saved? I don't want to put a lot of money into it as it's already 6.5 years old. I have a 2010 27" i5 iMac that I can use it for spare parts for (mostly just the LCD screen as the HDD are different models, I tried to swap them in my troubleshooting efforts and found they have different temp sensing cables)

    Any experts out there with a clue?

    TIA…..Nano
     
  2. vkd macrumors 6502a

    vkd

    Joined:
    Sep 10, 2012
    #2
    Sounds to me like the graphics card. Why not try putting the one from the 2010 27" i5 iMac in and testing?

    Is the 2010 iMac severely out of order? Why not get it going with parts from the 2009 iMac?
     
  3. mzd macrumors 6502a

    Joined:
    Jul 25, 2005
    Location:
    Wisconsin
    #3
    Something very similar happened to my late 2007 24" iMac. Initially it was a problem with the hard drive, but after reformatting the HDD came back clear in Disk Utility. Tried a restore from Time Machine, tried a clean install, tried a clean install of an older version of OS X, tried installing on an external HDD, but no luck. The screen would just go to white about 1/3 of the way through the boot progress bar. I could boot in Safe Mode, but that didn't get me very far. I gave up after 3 weeks of messing with it and just got a new iMac. I knew the 2007 was on its last legs, but it would be nice to figure out the cause and get it running as a basement media computer.
    So unfortunately I'm not much help, but I'll be watching this thread to see if you figure anything out.
     
  4. stuartak macrumors member

    stuartak

    Joined:
    Feb 21, 2016
    #4
    Random faults of this nature tend to point to the graphics card " hanging on boot screen ", "blacked out screen", "stripes "etc , once it starts doing it the card will eventually fail. If you have a donor machine the graphics cards are interchangeable even though they are not the same model , just swap it with its own heatsink , OSX will figure out the right driver. Also you can switch the drives as long as you also switch the temp sensing cable with them. Its from 2011 that the HDD has no separate temp sensing cable. I find it handy having a bootable USB with OSX on it when fooling with hard drive swaps and faultfinding drive issues as you can boot from the external USB into disc utility without relying on a recovery partition on what my be a corrupted drive.

    The other last resort "fix" is "baking " the graphics card which has worked for me several times , sounds crazy but its true.
     

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