These are primarily media consumption, internet surfing, ultra thin laptops. Intel only announced TH2 in June of 2013 so there's no way they could have included it in the MBA Mid 2013 edition. The one Mac that Apple did give a Big Sur pass, the Macbook Air, mid 2013, only has a single TH1 and not a TH2 port.

The 2013 Mac Pro 6,1 has 6 TH2 ports so it made the cut for Big Sur. The Late 2013 27' iMacs have more than adequate GPU and CPU performance to run Big Sur, it's just that they were stuck with the older TH1 1st gen ports. The Mac Pro 6,1 of course, didn't ship until late December of 2013. That's why the Late 2013 MBPs get Big Sur support. The late 2013 MBP was released in the latter part of October that Fall and had TH2 ports. The Late 2013 iMac was announced, 9/24/13, just before TH2 was ready to be included in a Mac. The Mid 2014 15,1 iMac has TH2 ports, the 14,2 iMac doesn't. It looks as if they use other criteria to determine which Macs can install and run the latest macOS.Īfter a good amount of research, it's clear to me now that Apple drew the line for Big Sur support at Desktop Macs and Macbook Pros that have Thunderbolt 2 controllers. It's more than capable of running Big Sur, especially if a 2014 Mac mini is able to. There seemed to be no good reason to drop the Late 2013 iMac from their list of supported Macs.

When Apple announced which Macs would still be supported by macOS 11, I found it hard to believe they dropped support for 2013 iMacs and kept support for the 2013 MBP and 2013 Mac Pro. Building a CustoMac Hackintosh: Buyer's Guide

Late 2013 imac trim for samsung