Replacing graphics card on iMac 8.1?

Discussion in 'iMac' started by guapagirl, Aug 3, 2015.

  1. guapagirl macrumors newbie

    Aug 3, 2015
    Hi all,

    Apologies for my first post being a plea for help, but I've looked everywhere for an answer.

    My iMac 24" early 2008 went caput. The screen was covered in a kind of herringbone pattern as per the first photo. I tried the single user boot and the fsck repair attempt. It came up that files had been modified but couldn't be repaired and eventually it was suggested on another forum that it was a hard drive failure. I bought diskwarrior to try to recover as much data as possible and bought and installed a new hard drive, but the same graphic issue came up as per the second photo.

    So it was then suggested that it was the video card.

    After having a look online, it looks like the video card is replaceable and being a have ago kind of gal (who is also almost broke), I want to try and do it myself. Thing is, which one do I get and are they available in the UK?

    Any help, advice warnings or whatever gratefully accepted! :) IMG-20150529-00094.jpg IMG_20150731_213739.jpg
  2. DaveAmbler macrumors member


    Jul 15, 2010
  3. Samuelsan2001 macrumors 604

    Oct 24, 2013
    Your best bet at this stage will be ebay.....
  4. guapagirl thread starter macrumors newbie

    Aug 3, 2015
    Thanks for the speedy replies.

    I saw that on ifixit and have used the site to swap out hard drives and do fixes in the past. The difficulty is knowing which one to try and get. According to the serial number it's one of the Gforce ones, but that also said I have a 500gb hard drive but it's actually a 1tb HD, and it now (after spending half the day looking online) looks like I need to get the absolute correct one for it to fit.

    I think so. I will have to pull it apart and hope it's the more available (and cheaper) radeon rather than the harder to find, more expensive (and often faulty) Nvidia one.

    I fear in reality I'll have to bite the bullet and save up for a new machine though :(
  5. sebastius macrumors newbie

    Feb 22, 2015
    Don't buy a 'new' graphicscard. All of them have the same problem and the ones on ebay or at shops are most likely refurbished/reballed/reflowed cards. They WILL fail again and probably soon.

    Easier is to reflow your own card. Or have it done somewhere locally. Don't go for reball, it's a hefty premium for only a short extension on its lifetime. Reflow is something you can do once or twice.
  6. Brian33 macrumors 6502a

    Apr 30, 2008
    USA (Virginia)
    Hi. I've got a 24" Early 2008 iMac 8,1 (using it right now). The graphics card is replaceable in these machines. My understanding is that you can use either one of the two cards that were originally used in the 8,1. In other words, I don't believe you have to replace yours with the same card you now have.

    Mine has the ATI Radeon HD 2600 Pro (256 MB), and I recommend you look for one of these and NOT the NVIDIA card, because from what I've read the NVIDIA ones fail much more often. In any case, try to make sure the card was made for a Mac; I believe that there was also a version of the ATI Radeon HD 2600 Pro for PCs, and it will not work in our iMacs (at least not without making flashing the firmware or something like that, that I know little about).

    This image from the 8,1 repair manual shows the Apple part numbers for the two graphics cards: 24-inch Early 2008 lower.png
    Here's the matching image for the rest of the iMac: 24-inch Early 2008 upper.png

    Hopefully that will help. I don't have much opinion on the reflow option, or even whether the graphics card is the cause of your problem, as luckily mine is still working. (I am curious, though, about what release of OS X you are running. I did have serious graphics problems under later versions of OS X 10.6 (Snow Leopard) that, oddly enough, were solved by using earlier versions of the graphics driver kext files.)

    Good luck! iMac 24-inch Early 2008 lower.png iMac 24-inch Early 2008 upper.png
  7. almarzeta macrumors newbie


    Jan 29, 2018
    Hi Brian! would you care to tell me how and if so, could I downgrade the kext files from a ATI Radeon HD 2600 Pro? my imac is on OSX El Capitan 10.11.6
  8. Brian33 macrumors 6502a

    Apr 30, 2008
    USA (Virginia)
    Here's the thread where I got my information, but beware it's 121 pages long now!

    You'll have to figure out, for your particular machine, which kext files would need to be replaced with older ones, and find the older versions somewhere.

    This solution worked for me for more than 4 years, but in the fall of 2015 my 24" Early 2008 iMac became unusable, even with the "kext fix". I concluded at the time that the graphics card had failed (in a different way) completely, although I don't recall how I came to that conclusion. In any case, I reluctantly gave up on that machine. I think I was running Mountain Lion on it at that point. It's a shame -- I had set up a DIY (do-it-yourself) Fusion drive (512GB SSD + 1TB HDD) and the 7.5 year old machine was meeting all my daily needs perfectly well up to that point.

    I had plans to turn it into a plain DVI-connected monitor; I saw instructions somewhere, and at least a couple of years ago it seemed that the proper LCD driver board was available, but I haven't gotten around to it.

    I wish you good luck.
  9. Fishrrman macrumors G5


    Feb 20, 2009
    At ten years old... it's really time to be... shopping for a replacement... (sigh)
  10. almarzeta macrumors newbie


    Jan 29, 2018
    Thank you Brian! I'll dig up on that info I appreciate your answer, although I think the solution is to completely install a GPU replacement which its a shame because even if the iMac has live long enough I still think is suitable for my daily needs as well, shouldnt be this hard to find a replacement but I havent got any look since I do not live in the US.
    --- Post Merged, Jan 31, 2018 ---
    yep, you're right... I think as of today the prices I've seen are insane, I think most of em are not updated given that they are way over the iMac price itself

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