Hi Loloflatsix (and everyone else), I never realized that this post on TonyMac ever existed. I am amazed at what you and others have done to have this post be this active and alive! Cool stuff! I too have two Asus Prime X299-DELUXE (version 1) motherboards. My main system runs a i9-7980XE CPU, 64GB of GSkill 3600MHz of RAM and 2 x AMD Vega Frontier Edition 16GB GPU's. My backup system runs a i9-7960X, 32GB of GSkill 3200MHz RAM and a XFX Radeon VII 16GB GPU.
I (at one point and time), had KGP (Klaus) help and guide me to get my main system working, but mine haa a slightly different twist. I have 3 x Asus 28" 4K monitors working side, by side, by side. Hence the reason why I needed 2 GPUs to have more RAM working my monitors better. Now, I've been using MacOS X 10.15.0 for quite some time and it's been great, but I'm needing to upgrade to either 10.15.7 or Big Sur (beta). For some reason I'm not able to update to any further than 10.15.0, because when I do, the screens just go black on boot. So that's the reason why I haven't updated my OS.
So I after reading about 35+ pages (sorry, haven't read ALL 59 pages yet), I decided to experiment and use Loloflatsix's EFI file (on Post #87), and try it out on my backup system using (at first) 10.15. It worked like a charm!!! Faster boot time (by about 10 to 15 sec faster). Then yesterday I decided to try the latest Big Sur 11.0 (beta 10) and everything installed nicely, but when it finally went to the boot screen (where you see the Apple logo and the processing bar below), it just stayed there and didn't go further for about 10 min. I then shut everything down. But decided to restart it and try again. Well I waited a little past 10 minutes and it actually started, where I was able to see the Big Sur screen saver. I guess I should've waited a bit longer, as I didn't realize it was still installing. Currently it's doing it's installing "thing" and I've been watching it (slowly but surly), work thought it's installing process. This is taking a very long time. I've been sitting here for about 30 min and it's still "setting up my Mac."
By the way, I was told by someone that the reason why my system was not able to update to anything higher than 10.15.0, was because of the older Vega Frontier cards and that updating to a better card (like Radeon VII), would work. Well doing this new install with the Radeon VII card looks like it's working so far. Would anyone know how true that is about whether or not the the Vega Frontier cards are the issue? Let me know what you can, thank you.
