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Successful iMac Upgrade to GTX 880M

Jason -

iMac Intel 21.5" EMC 2428

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iMac Intel 21.5" EMC 2428 GPU Card Replacement

4 uren

Very difficult

Mijn probleem

My daughter has a 2011 27” iMac (base model) and it just cannot keep up with modern games. XCOM 2 for example was unplayable even at the lowest settings. I decided to try an upgrade to a GTX 880M and used this guide as baseline even tough it was for the 21.5” model.

The GTX 880M was purchased off of eBay and reportedly came from an Alienware Laptop.

Here is a comparison of it and the 6770M the iMac had before…

Mijn oplossing

The upgrade went great! The 880M is longer than the 6770M but still fits, especially because we also replaced the HD with a SSD. The difference in playing games is amazing, most games auto-detected the new card and changed their settings to the highest settings. XCOM 2 runs perfectly at medium settings, which is comparable to my 2015 5K iMac.

This upgrade was hard, but really worth it!

Mijn advies

To get the computer to boot the first time I needed to use Safe Mode by holding down the shift key as soon as I hear the start up chime.

Once booted into safe mode, installing the nvidia Web Drivers made the system work perfectly. I also installed the CUDA drivers, but thats not required.

Web Drivers:

CUDA Drivers:

The computer will run really hot after the upgrade because the card has a much higher TDP (35W vs 122W). To prevent overheating I used SMC Fan Control to set the fans to a minimum speed of 2200 rpm.

SMC Fan Control:


- Gaming performance is amazing.

- Can play games we couldn’t even launch before.

- nvidia provides a driver!!! :-)


- Requires nvidia driver (check for updates before OS updates)

- Loss Boot Screen and Brightness Controls

- Higher Fan Speeds = Louder Mac

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62 opmerkingen

Hi Jason, thanks for you story

Did you use Alianware card as is, with original firmware(not Apple's firmware)?

Did you solve the problem with the brightness control?

drugoyzvuk - Antwoord

Yes, I used the card with the original firmware. No, the display is stuck at full brightness but that's not an issue for me so I haven't messed with it. System is still running great, now on macOS Sierra.

Jason -

To make a non-apple provided Nvidia graphics card work in macOS Sierra you need to do the following…

Start the computer in safe mode by holding shift.

Get your BoardID by running this command in terminal

echo "<result>$(ioreg -rd1 -c IOPlatformExpertDevice | awk -F'["|"]' '/board-id/{print $4}')</result>"

Open the AppleGraphicsControl Kext using this command

sudo nano /System/Library/Extensions/AppleGraphicsControl.kext/Contents/PlugIns/AppleGraphicsDevicePolicy.kext/Contents/Info.plist

Use the arrow keys to go down until you see <key>ConfigMap</key> followed by a bunch of keys and strings.


IF IT IS LISTED: Change the string to <string>none</string>

IF IT IS NOT LISTED: Add it in the same format as the ones listed.

Save the file by pressing Ctrl+O, then enter.

Exit by pressing Ctrl+X

Rebuild the kernel cache using the following two commands:

sudo kextcache -system-prelinked-kernel


sudo kextcache -system-caches

Have Fun!

Jason - Antwoord


Do you know, Is there a list of supported Nvidia video cards for this iMac?

I'm looking for not so hot chip, performance is not the main goal. May be modern GTX 9xxM or GTX 10x series

drugoyzvuk -


This fix works perfectly for osx sierra, but no longer works for high sierra. Any suggestions on getting this up and running on the new OS? I checked and verified csrutil was disabled before I ran the setup, I think apple really wants us to buy new machines now.. Would so be great if anybody has a fix!

Yusuf Ibrahim -

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