I have the ATI Radeon HD 4850 graphics processor with 512MB of GDDR3 memory installed on an i5 iMac 27inch setup. Given that my current card is malfunctioning and that versions of that card are prohibitively expensive, which cards could I theoretically upgrade to?


2 Answers 2


According to iFixit.com, you can upgrade the video card to the same one that was in the last 2011 model:

If you are using the iMac 27" late 2009 or 2010 model for games you might want to upgrade your graphics card to the 6 series of the last 2011 model.

For any other reason this upgrade is not recommended as the power gain is only noticeable in games.

Since you have to replace the card, it's definitely a good time to look at an upgrade:

The ATI Radeon 5xxx series from the 2010 should works as well, but they are very rare for some reason. For the price and convenience, I would go with the 6xxx series if upgrading.

If I had the time to search and scour the web for a good deal, I would try to get the 6970 at a good price, but I don't think I would spend the extra money on upgrading a computer that was technically 7 years old with a graphics card that was 5 years old. Especially so since the graphics upgrade wouldn't be noticeable unless I was gaming. And if that was the case, I would probably have a console or a PC...but that's just me.

The iFixit link I provided has an excellent step by step on how to replace this card.

  • Thanks! So this card (Apple iMac 27" A1312 ATI Radeon HD 6970M 661-5950 Mid-2011) would be compatible?
    – Ghost Koi
    Commented Aug 15, 2016 at 19:52
  • According to ifixit, yes. I did some reading and it appears that interface is the same. Obviously OS X ships with the drivers that you need so you should be good to go.
    – Allan
    Commented Aug 15, 2016 at 19:53
  • Well its August 2021 and my late 2009 iMac, which runs great with its upgraded SSD and replaced optical drive with SSD just had the GPU go out. On eBay as of today, you can pickup a Mid 2011 6970m to upgrade the late 2009 iMac GPU for about ~$250 (including the 3-pipe heatsink). You can take a chance and order international from China for less but those cards are usually PC GPUs pulled from an old Dell or Alienware laptop and they flash the GPU firmware which may or may not work. Commented Aug 19, 2021 at 17:11
  • 6970m upgrade video youtube.com/watch?v=9dPsH1zIQMs Commented Aug 19, 2021 at 17:16

The Radeon HD 6770M is compatible — see here. I don’t know if it will be any cheaper, though.

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