Late 2012 iMac 27" - latest compatible logic board?

[JPamplin]

Howdy,

I have taken possession of a late 2012 iMac 27" - but it's stuck on Catalina.

Has ANYBODY replaced the logic board with a later model? If so, assuming all other things being the same, what's the latest year logic board I can stick into a late 2012 iMac chassis / power supply / screen that would be pin-compatible and "just work"?

Please help - I appreciate your collective guidance,

JP

 

[TwoH]

Only other compatible would be a 2013 which again, maxes out at Catalina. 2014 upwards are retina and would require a different LCD.

I believe the antennas are different starting with the retinas too and aren’t fully compatible with the older 2012/13 antennas on the chassis

 

[Juicy Box]

I have taken possession of a late 2012 iMac 27" - but it's stuck on Catalina.

I thought I saw somewhere people getting Big Sur on the Late 2012.

I wasn't interested in it, so I didn't pay much attention to it, but I thought I saw that HW wise, the Late 2012 runs Big Sure, with the exception of the wifi antenna.

If I can fine it, I will post it for you.