I’ve been running the Acidanthera builds of OC since August of last year in my edit suite (OSX 10.13.6) and it has been completely stable. The vanilla guide tells you every thing you need to know to setup the config.plist for most modern chipsets, X299 and AMD included. The future looks bright!
It's not that hard if you give it a shot, and you get to figure out the exact correct slide value you should be using.
Failing that, disabling as many things as you can in the bios gives you greater chance of success :)
Almost certainly a bios update problem that changed the size of the memory map.
I highly recommend this read on the subject:
I've been trying to dive deeper into SSDT understanding, and I dumped the native SSDTs for my motherboard (Z170-UD5 TH, BIOS F22g)
And this native SSDT throws errors when decompiled and recompiled. (I don't think it is causing problems with the system, but just in case...) Thoughts?
I don't use ShowPicker, I let OC boot straight to the Apple logo (aka my default boot option). Used in conjunction with AppleUsbKbDxe.efi, I can still access the picker by holding option key, which is more 'mac-like' behavior. It's tiny on my 4K screen but functioning just fine :)