Using older MacOS versions (supported)
According to this
list the Nvidia drivers are part of macOS since 10.8.3. You might check this out on your own. At least on recent successful upgrade of an iMac 12,2 with macOS 10.10 can be reported here.
Installing MacOS Sierra (supported)
Supported MacOS version can be installed using the original Apple installer. To avoid the black screen issue install this
package.
Installing MacOS High Sierra (supported)
Supported MacOS version can be installed using the original Apple installer. To avoid the black screen issue install this
package.
Installing this last supported macOS version brings in the latest firmware. There will be unlikely ever new firmware versions since High Sierra went out of Apple support these days.
Installing MacOS Mojave (unsupported)
The recommended method is to have High Sierra as your primary OS and install Mojave alongside on a separate partitions or APFS container partition. So if anything goes wrong, you can still boot back into High Sierra to fix issues. High Sierra offers a working recovery partition, too.
This is a two step installation. First you will use the
@dosdude1 patcher and later install a package needed to address the hardware changes you made by changing the GPU.
1. You could preinstall Mojave before changing your GPU. Use
dosdude1's Mojave patcher to do the install.
Important: While running the Post Install tool, make sure you deselect the Legacy Video Card patch option (since you will using a new, compatible metal graphics card).
2. GPU and machine related patches: (see next section common macOS problems)
Late 2009, Mid 2010: To avoid the black screen issue install this
package or follow instructions this
post.
Mid 2011: Install this
package to avoid sleep problems, black screen etc. or follow this
post.
Installing MacOS Catalina (unsupported)
The recommended method is to have High Sierra as your primary OS and install Catalina alongside on a separate partition. So if anything goes wrong, you can still boot back into High Sierra to fix issues.
This is a two step installation. First you will use the
@dosdude1 patcher and later install a package needed to address the hardware changes you made by changing the GPU.
Important: Post-install patching has changed since Mojave.
Patching is now automated if your SMBIOS is detected to be an unsupported machine. Currently, only the 2011 iMacs have the "Legacy Video Card Patch" disabled by default. You will avoid this patch (since you will use a new, compatible metal graphics card) and will need to modify a plist file if you are using a 2009/2010 iMac with a Metal compatible video card or more easily while building the patcher, you can go to the "Options" menu and de-select "Auto-Apply Post-Install Patches" to avoid this.
Important: While running the Post Install tool, make sure you deselect the Legacy Video Card patch option (since you will using a new, compatible metal graphics card).
1. The process for Catalina is similar to Mojave as mentioned above. Use
dosdude1's Catalina patcher to do the installation.
2. GPU and machine related patches:
Late 2009, Mid 2010: To avoid the black screen issue install this
package or follow instructions this
post.
Mid 2011: Install this
package to avoid sleep problems, black screen etc. or follow this
post.
See next section to manually fix this issue if you have accidentally installed this patch. Best option is reinstalling Catalina from the scratch!!
Installing MacOS Big Sur (Release 11.0.1 20B2029) (unsupported)
The recommended method is to have High Sierra as your primary OS and install Big Sur alongside on a separate partition. So if anything goes wrong, you can still boot back into High Sierra to fix issues.
Having a Metal GPU makes your iMac Late 2009, Mid 2010, Mid 2011 Big Sur compatible. To make the package perfect and nearly fully compatible you could have installed an WiFi/BT
upgrade, but it is not necessary to install and run Big Sur. The stock old Atheros WiFi card will be supported.
We managed to get all necessary patches for all iMac hardware to be included in the current state of the art Big Sur patcher (the iMac fork of the
@Barry K. Nathan micro patcher). There will be no manually installation of more extensions as with Mojave and Catalina, before. To understand the installation and patching process please follow the instructions provided on the Github download page step by step! The patcher will auto detect the installed GPU.
To avoid a kernel panic on boot of the Big Sur installer all users of the 2009 and 2010 iMac systems will have to use a special OpenCore based solution, to understanding the reason please read this
post. This applies to all Kepler cards used, too. The most easy way will be to use the Catalina Loader provided here. There will be an update to the Catalina Loader using OC 0.6.3 including this patch, too. Check this
post about the process of installation and normal boot of Big Sur using OpenCore.
Please keep in mind that the development is still ongoing and the developers on the
thread cannot really support you with installation issues right now. You need MacOS and UNIX experience with the Terminal app and the command line to accomplish this task.
Notes:
- The stock WiFi and BT works properly patched, too. No HandOff and no Continuity, of course.
- AMD based systems offer 4K H.264 and 4K HEVC with Big Sur, again.
- Nvidia based systems lack currently still of iGPU based H.264 acceleration.
- Since all iMac 11,x models will need an OpenCore (OC) solution with Big Sur we have now only a few systems remaining working without OC, the iMac 12,2 using NVIDIA cards marked with a ++ in the table above. Due to this fact all systems using OC will have to use the Catalina Loader (CL) and the attached 0.6.3 (or later) EFI folders. These are preconfigured to inject all other extensions needed like Lilu, WhateverGreen, AppleBacklightFixup, PolarisBoost etc.
- All ++ card users with iMac11,x will need the special version of the AppleBacklighFixup.kext published here on the CL. It is the same link as in the table above. Please just replace the file on the CL in the EFI/OC/Kexts folder if and only if you experience any oddity with the backlight control.