2011 iMac Graphics Card Upgrade

Preamble (Last Updated 12/03/2020 - added color depth issue in FAQ)

This is not a plug and play solution!

You have probably found this thread because your iMac late 2009 to mid 2011 is having problems caused by the graphics card. It is well known that these graphic cards are problematic/defective.

We have great news for you! You can install another graphics card that does not require much more effort. In addition, this will allow you to install more recent versions of MacOS. This thread has over 450 pages of useful information BUT the good news is all of that information has been summarized in this first post. It is HIGHLY recommended that you read through this post before asking questions. Then, reread the information. You will appreciate that the more experienced users cannot spoon-feed all new users. This distracts them from working on the files and tools that make all of this possible.

Before you post a question you may consider to add a signature to your account settings reflecting your machine type, graphics card, and possible even the problem you have. This signature sticks with every post you make and helps other to keep track and understand what is going on.

Warning:

1. Getting a 7-8 year old used Nvidia card may cause some new problems. These card may be already (half) dead and the current owner knows exactly why he wants to sell the card after years. Do not jump into the first cheap deal, try to get unused spare parts. Most complaints on this thread (hundreds of posts) were caused by cheap old dead cards and endless trials to "repair" these by installing software. This will not work! Some Far East sellers offer new cards with new BIOS chips soldered on. Ignore those offers. There must be a reason to add manual labor soldering a new part on it. Most likely because the card does not work. We have seen also cards with unexpected small BIOS chips not capable of storing the new developed BIOS firmware versions available here.
2. Most HP AMD cards will not do the POST (Power On Self Test) in the Mid 2011 models - these cards will not work! Please read the AMD section below.

Enjoy!


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Original Post from @MichaelDT June 14th, 2013.

I will be attempting to upgrade the MXM card in my 2011 21.5 iMac from the factory 6770m 512mb to a NVidia 675m 2GB. I choose this card because the chipset already has support from 10.8.3 onwards and affordability for an experiment. I am hoping that it will work without flashing like many of the other non MXM modern graphics cards (UEFI support) do in 64bit EFI Mac Pros ( I may loose the initial boot screen). But if all else fails I will attempt a flash. I will report back my findings when the card arrives (from Hong Kong). Wish me luck hopefully this will give those of us with the last modular iMac a path forward.
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