macOS Big Sur Does NOT Boot with iMac14,2 System Definition

[amerv]

If you have the time, tell us the parts in your build.
And if you can boot on 17,1 - run your config through OpenCore Configurators config checker.
And of course, not to be insulting but double check you've no kext updates with Hackintool or something

- I don't use hackintool
- I always use ocvalidate tool to upgrade opencore
* something is related to iGPU but I don't know what

https://github.com/acidanthera/WhateverGreen/blob/master/Manual/FAQ.IntelHD.en.md

 

[pepperdotnet]

My build is a Lenovo ThinkStation E20 (Desktop 3 in my signature): model 4220 / Xeon 3430 / GeForce GT 710 with Clover 5126 (updating to 5137 fails but that's another issue I guess) and Catalina 10.15.7

It's working great with Catalina with the iMac14,2 system definition. But, if I want to attempt Big Sur on this thing I have to use something newer. Everything else I have tried so far gives me a black screen after the Apple logo and the bar gets about 3/4 of the way across. It's still functional because I can use Screen Sharing from another machine to view it. Just nothing on the local display. If I change it back to iMac14,2 it is happy again.

The newer iMacs in the System Information "Displays" area it shows using a Built-in Display with a resolution that my current display (1920x1080) is incapable of.

Is there some Big Sur supported system definition which might work for me? Or is the thing just too old to go any further.

EDIT: Never mind, I've been using the VGA connector since forever, apparently that was the issue. Switched to an HDMI cable and it's working fine so far as an iMac18,1.

I will leave this here for reference. Some testing of basic functionality and reading of articles before I attempt Big Sur.

 

[Wierzciu]

It's not true it's not possbile to run Big Sur on iMac 14.2 - it's posbile but first You must install system with EFI as iMac 15.1/+ .
If You do it, now You can run Big Sur with EFI as iMac 14.2 but You must ad, bootflag “ -no_compat_check ” .
This work fine on my setup