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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 hours

Very difficult

My Problem

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…

My Fix

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!

My Advice

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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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 - Reply

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 - Reply


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 -

Hi Jason

i have mid 2011 imac. Recently i just upgrade processor from i5 to i7. Now my imac running on i7 with osx sierra. I just bought gtx 880m from ebay.

Before i replaced with new gpu. I’m installed Cuda and nvdia driver based on my firmware.

Then i changed from my old GPU to new GPU gtx 880m.

On the gtx 880m, there is metal bracket and i have to removed and swap with bracket from my old gpu.

on your tutorial, i try to edit code from terminal but doesn’t work. (Still using my old gpu)

then when i replace with with new gpu, hold shift button. I hear sound from starting, but the monitor black screen. And make fan noise very loud.

I thought it because i install new ssd, even already use the thermal cable, the sound fan still loud and i still need to install gpu fan software.

Do you have any advise for me?

Kayana photography bali -

Hi Jason, I am trying to do the same upgrade but with the 6790M - also taken from an Alienware laptop. I installed the GPU, but the iMac does not start up. I had to remove a metal bracket on the GPU that was making the holes where it connected to the heatsink too small for the screws (am thinking this maybe damaged the card?)

How did you get around that issue? Did you also have to remove the metal bracket?

Thanks in advance!

joseph mullen - Reply

Hi Joseph did you get that 6970 alien wear card to work in your Imac..i’m thinking of trying this but would love to here what you did t get it working

Matthew Bryan -

i did the same with GTX 880m (8g DDR5) on my iMac 27 2011 under Sierra build 16C67.

Performances are "not really good" (see benchmark comparison with GTX 980m).

i have managed the info.plist by adding the board id.



Here in the next post the performances of the graphic card:

catalizer undeuxtrois - Reply

CUDA-Z Report


Version: 0.10.251 64 bit

OS Version: Mac OS X 10.12.2 16C67

Driver Version: 10.14.20 355.10.05.15f03

Driver Dll Version: 8.0

Runtime Dll Version: 6.50

Core Information


Name: GeForce GTX 880M

Compute Capability: 3.0

Clock Rate: 993 MHz

PCI Location: 0:1:0

Multiprocessors: 8 (1536 Cores)

Threads Per Multiproc.: 2048

Warp Size: 32

Regs Per Block: 65536

Threads Per Block: 1024

Threads Dimensions: 1024 x 1024 x 64

Grid Dimensions: 2147483647 x 65535 x 65535

Watchdog Enabled: Yes

Integrated GPU: No

Concurrent Kernels: Yes

Compute Mode: Default

Stream Priorities: No

catalizer undeuxtrois - Reply

Memory Information


Total Global: 8191.81 MiB

Bus Width: 256 bits

Clock Rate: 2500 MHz

Error Correction: No

L2 Cache Size: 48 KiB

Shared Per Block: 48 KiB

Pitch: 2048 MiB

Total Constant: 64 KiB

Texture Alignment: 512 B

Texture 1D Size: 65536

Texture 2D Size: 65536 x 65536

Texture 3D Size: 4096 x 4096 x 4096

GPU Overlap: Yes

Map Host Memory: Yes

Unified Addressing: Yes

Async Engine: Yes, Unidirectional

Performance Information


Memory Copy

Host Pinned to Device: 6339.17 MiB/s

Host Pageable to Device: 2439.6 MiB/s

Device to Host Pinned: 6281.4 MiB/s

Device to Host Pageable: 2455.58 MiB/s

Device to Device: 53.7525 GiB/s

GPU Core Performance

Single-precision Float: 2469.78 Gflop/s

Double-precision Float: 119.52 Gflop/s

64-bit Integer: 126.97 Giop/s

32-bit Integer: 505.607 Giop/s

24-bit Integer: 505.988 Giop/s

Generated: Sun Dec 25 10:51:21 2016

catalizer undeuxtrois - Reply

i have a 2009 27" iMac. I was wondering if this upgrade would be possible on it. if it was, am I right to presume that I would need the Radeon HD 6970M GPU's heat sink to carry out this upgrade.

brian moran - Reply

Yes you will need it.

catalizer undeuxtrois - Reply

This is effing amazing! You did the upgrade I didn't know I needed.

I did have one question related to power: The Radeon HD 6770 requires 35 Watts to run and I think the 880m is in the area of 100. How well does your iMac's power supply cope with the increased power draw? I think the Power supply is around 310 Watts?

William Paul - Reply

Hi Jason,

Would it have fit if you didn't replaced the HD with a SSD?

clint.iqr - Reply

Physically it would have fit, yes, but I would be worried about power and heat. Replacing the HDD with the SSD should help and if your going this far I highly suggest it for any extra 50 to 100 dollars the performance boost of an SSD is well worth it.

Jason -

Quick question, why not upgrade the RAM first? Games on 4GB RAM may be slow.

Mark McInnis - Reply

hehe, I did I just hadn't put it back in when I took the pictures. It has 32 GB of ram.

Jason -

I'm thinking to upgrade the gpu on iMac 27" 2011 to GTX 770m/780M or GTX 880M

Under Bootcamp Windows 10, can the brightness be dimmed down in any way?

Also, will the external monitors work through display port-hdmi?

Nestor - Reply

Sadly I haven't tried either. I don't think brightness will work though because its still using the apple driver.

Jason -

Hi Jason,

These are the technical specifications of my iMac 27 (mid 2011) osx Sierra:

PROCESSOR 3.4GHz Quad-Core Intel Core i7 MEMORY 8GB 1333MHz DDR3 SDRAM - 2x4GB HARD DRIVE 1TB Serial ATA Drive+256GB SSD GRAPHICS AMD Radeon HD 6970M 2GB GDDR5

Yesterday my graphics card stopped working (computer blocked with a vertical column screen). I found your guide very interesting, and I would like to upgrade the graphics card, i'm unsure whether to buy the GTX 880M or the GTX 980M !!

Do you think this configuration also works with the GTX 980M graphics card?

I would like advice on how to proceed, thank you !!

Lorenzo - Reply

I would get the 880M because of price. I don't think the more expensive 980M will provide much of a benefit over the other. Also, I'm not sure the card will fit if you have the 2nd hard drive installed but I haven't tried that.

Jason -

This is great -- thanks so much for posting it. We're about to try this with a professor's iMac, but I was hoping you could answer some questions first:

1- A year later, is everything still working? I'm worried about the extra heat damaging things long-term.

2- Any guesses whether this would work with a 970m or 965m? Again, concerns over power draw & heat (& noise)... I haven't found any successful reports online.

3- This computer still has an HDD. While we're opening it up, we were going to put in an SSD. We're not sure whether to use the dual-drive kit, or just replace it -- I'm worried there wouldn't be enough space for both plus the extra size GPU, and the HDD means extra heat. Thoughts?

Again, thanks so much for your post!

peternorthup - Reply

You're most welcome!

1) YEP! Everything is still working great and it sees almost daily use. It does get very hot though and your mileage may vary :-)

2) Yes, I would think both would work, but power is the biggest concern. Try to get the one with the lowest power requirements.

3) I don't think the dual drive kit will fit with the card, but I could be wrong. I would recommend just replacing it with a large SSD or a small one and an external drive. Also, yes, the extra HDD is more power and more heat, which is bad. :-)

Jason -

Hey there, I am also interested installing a 9xxM card, only I would be using a 980M. So far my research tells me that a 980M won’t work, but I was wondering if you ever got your system working with a 965M or 970M since they’re part of the same series as the 980M. If you did get the card working, was it the same process Jason used, or were there specific tweaks you needed to make? Thanks in advance!

Parker Swift -

Hey Jason..

would this be the card you bought?

Marko Knok - Reply

Hi Jason

dose your System Reporte now list your iMac as Metal compatible or the only Plus that its a lot Faster. The reason i am asking is that Bilzzards WOW is now informing me that my iMac will no longer be able to run the upcoming version because Metal is missing. Or do i Need additional tweaks of a ktext to fool the system into thinking im using a better mac that i have.

{iMac 27” mid 2011, 3,4GHz i7, 32GB Mem, Wifi Replaced to make it Handoff Compatible}

Stephan Hauser - Reply

Hey Jason, I’m trying to add this exact gtx 880m to my 2011 27inch iMac, but I’m not getting the 3rd light on the board to light up that signifies the new GPU card is found. My OS is currently on high Sierra - and I have already downloaded Nvidia web drivers. Is this card bad? Or is it because of high Sierra that it won’t turn on? I tried booting into safe mode for well over 10 minutes holding shift, but it did not work. This thread shows El Capitan and Sierra that it works for, but are you on High Sierra now?? Please help! Thanks!

Justin Stewart - Reply

Hi all,

My 2011 27 inches iMac graphic card died a second time yesterday, and I am also considering changing it by a 780m or 880m. Justin have you managed to get your machine to work on High Sierra. Jason can you be of some help regarding High Sierra compatibility?

Thanks for your help guys!

Nicolas Giorgi -

Hi Jason!

Could I still use an upgraded iMac as external monitor for my MacBook Pro via Mini DP? Sometimes I need it.

Ramiz Gasanov - Reply

Time has came to me to upgrade the garbage AMD 6950M to Nvidia on my 2011 mid 27” i7. Found the latest web driver for High Sierra Mac OS here ”

wish that will work for Quadro mxm card too

Kamiiyu - Reply

yes it most probably will work with El capt/Sierra. NOT high Sierra!

Michael Klaus -

Hi All

I saw that the post is in 2016, I wanted to know if after 2 years, and with high sierra is always possible to upgrade the video card, I have a mid 2011 with i7 3.4ghz, 32gb ram ddr3 1333mhz, ssd 256gb and 2tb hdd, I would be interested in upgrading and then installing Mojave, do you have any news? thank you

Andrea - Reply

Hi all,

i have an 2010 21,5” iMac with a faulty GPU.

I found a cheap GTX 260 from an Alienware Notebook.

I have put this GPU into my iMac, i hear the Startup-Sound, but i got only the first two LED’s light up. Is this normal, if the GPU doen’t have Apple Firmware on it ?

No screen anyway. I have tried High Sierra so far, but no luck. I will try El Capitan/Sierra.

skclan - Reply

Did you managed to get this working? tempted to try the same thing

TheOrangePulley -

Hello i want to know your VBIOS Version and is it working with High Sierra?

Roman Pi - Reply

Hi!!I’ve a iMac late 2009 i7 and my graphic card doesn’t work… I’d like to buy a new one, but the original ati mobile radeon hd 4850 512mb is impossible to find…Which other card can I buy that is compatible with my imac? I would be very sorry to throw away my imac just for the non-working graphics card ... thanks to everyone

Simone - Reply

Hi you can have a llok for ATI HD 6750m, ATI HD 6770m or ATI HD 6970m, if you look for Original card.

Roman Pi -

So once you do this kind of thing, is it effectively similar to running a hackintosh (just for the video card)? In that with each upgrade in the macOS, you will have to redo the nVidia drivers?

Milo Mak - Reply

Lucky to you, her iMac is still pre 2012. Try this upgrade on slim iMac (2012 onward) and you’ll need way more than disassembling the whole computer. Slimmer iMac models have their GPU soldered directly into the logic board. If the graphic chip gone, so does the logic board along with it.

Ferry Gunadi - Reply

Hi all!

I’m so glad to have found this thread!

I’m trying to fix a dead NVIDIA GeForce GTX 780M 4096 Mb on an iMac 27” A1419 (late 2013, 3.5 GHz Intel Core i7). the graphics card doesn’t work any more: I only get blue vertical strips on screen.

I not able to find the same card, so my question is: can I replace it by a newer one I can at least buy somewhere…

Thank you.

Jean-Marc ARZOUMANIAN - Reply

The loss of boot screen and brightness control can only take place on Sierra-High Sierra and above. On previously MacOs versions works like a charm. Thats because from Sierra and above Apple add some parameters on her Os so only original Apple components can be added on her products. Is the same thing like the home button problem on iphones.

GamingHorde - Reply

How do we fix this? Who sells pre flashed Imac 980m’s?

Albert Einstein - Reply


I’m not sure if someone has some successes like me but I’ve replaced my Radon 6970M to NVIDIA GTX 880M 8GB without any problem is working on High sierra 10.13.6 only brightness not working but you need to install from Appstore Brightness slider and everything is like normal

KratosMac - Reply

hello, is your 880m from dell/alienware

crapthings -

and what did you do after 880m installed ? did you modify the kext like above?

crapthings -

krato you followed Jasons instructions to get your’s to work on High Sierra? The drivers he shows that work are from El Capitan. Did you use the El Capitan drivers? Or did you go searching and follow this link : to obtain the Sierra/High Sierra drivers? Also did you download the cuda and nvidia drivers? I am very curious to know all of this. ALso thanks for the tip on the Appstore Brightness Slider! I have already purchased my GTX 880M and I am just wanting to do this correctly! I don’t want to mess up!

Manny -

No, I didn’t modify yet but I think I need too because when I’m trying play Metro Game is freezing after intro, so I’m guessing is because Borard ID and the problem is I’m not able to modify info.plist file no chance to overwrite, I don’t know how Jason manages this file

KratosMac - Reply

Yes I have Dell/alienware

KratosMac - Reply

Hi Jason,

Could you tell if your GTX 880M card works on your 2011 iMac on Mojave fluently?

Currently I would like to buy this card (or the 860M / 875M model) but I read all kind of horror stories of unsupported NVIDEA drivers…

Hope you can tell more about your experience.

Thank you.


Arnold - Reply

Hey guys, same question than Arnold. I’d like to upgrade my iMac to upgrade to Mojave and play games. My questions are:

- Are all cards compatible or only some models (alienware only) ?

- Is it compatible with Mojave ?

Vincent Catillon - Reply


Any who wants to get some information about upgrade card send message on my e-mail “


KratosMac - Reply

@KratosMac i have sent you an email, if you could respond i’d really apprecaite it. any help is greatly appreciated!

Manny -

Hi Jason, thank you for sharing us your experience.

I have the same iMac and want to upgrade to a AMD Radeon HD 8970M 4GB  or Nvidia GeForce GTX 780M 4GB (I don’t need 8 GBs xD) any advice or recomendation? Choose one pls.

Have you found any site where you can see the compatibility?

Thanks in advace :)

Luis Angel - Reply

i do have a question. when you upgraded to 880m card did your diagnostic led 3 and 4 are all on when you first booted ?

dondrapersf - Reply

has anyone ever tried to use the 880m card with mojave or catalina?

Marcos Gazeta - Reply

Im also looking for a fix in high sierra!. I have the same problem as you Yusuf Ibrahim


Please anyone can you please revive this thread, this instructions are so scatterbrain. It’s not clear and concise… any help is greatly appreciated!

Manny - Reply

Theres a LOT more to this topic and it's not something to be attempted casually. The best place for all the latest info on upgrading the GPU in 2009 - 2011 iMacs is at:

Page 1 has a list of compatible cards and the current state of functionality as well as workarounds for many of the cards listed...

paul.capaldi - Reply

Hey guys,

I have problem with the 27 iMac 2011, the video card is done, I have tried baking but overheated it and one of the mem chips came down. i have put it back but I don’t think it worth trying. Now I have two options that are quick. I have found a broken similar card which I can try baking or a 512 mb nvidia card form a 21 inch imac same year that is working. Not sure if this downgrade would work smoothly and easily and how the radiator matches up. What do you think? Thanks.

Ferenc Maki - Reply

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