Chosen Solution
So, similar to Zach in other posts, I have successfully upgraded a 2019 27” iMac with 9600k and Radeon Pro 580X to a 9900k. I am interested in doing the same for one of the 2019 with either the 8500 or 8600 CPU’s. Looking at Apple’s site, the 8600 with 575x does have an option to upgrade to a 9900k. Does anyone know whether this would be a possible user upgrade? I see someone has unsuccessfully done so with the 8500 27” iMac base model. Understandably, this could be a limitation of the EFI; however, I question whether that was also just a poor installation of the 9900k. The retention mechanisms are tricky to reassemble in these iMacs.
To start with Zack’s system was an older Mid 2017 model which is why his couldn’t support the CPU’s he was looking at i7-8700K & i7-8086K as his EFI predates these CPU’s iMac18,3 OK lets look at your system: Your systems series iMac19,1 Genrally, Apple reuses the same logic board across the series just putting in the different CPU’s. Things are a bit different between the AMD Radeon Pro 570X, 575X or 580X. The AMD Radeon Pro Vega 48 is a very different chip and uses a different logic board configuration.
AMD Radeon Pro 570X, 575X or 580X
AMD Radeon Pro Vega 48 I have not gotten into upgrading this series so I can’t tell you if the low end boards have the needed EFI support for the higher end i9-9900k CPU. Given the costs and risks I think it safer to just get the higher end models from Apple than trying to upgrade such a new system to save a few hundred bucks and loose any warranty coverage.
