Ok tomorrow my Radeon RX 560 4GB arrives to replace my GTX 1050 Ti
1. Clean install Mojave: For more experienced hackintosh owners or those that want even better performance and compatibility, I'm recommending that you use Sniki's UEFI hot patching guide for the HP 6300/8300. What is "hot patching" and why use it ? It's a techinique where Clover patches the ACPI tables/DSDT on the fly. Instead of staticly patching the DSDT as we used to do, it's all done via SSDT or "secondary system description table" files. It's much more flexible than a staticly patched DSDT. Make one BIOS change and you'd need to re-patch your DSDT. Not good.
He has a fine tuned USB SSDT, audio SSDT and custom config.plist you can use. This means you'll get better USB performance and external devices will charge faster via USB etc. etc. That guide is in a rewrite for the latest Mojave version right now and should be posted in a couple of days so wait for that if you want to install 10.14.5 from scratch. Since the HP 8300 is his "daily driver" you can be certain everything will work optimally. A clean install is mandatory to use Sniki's guide. It won't work well if you try and just take bits an pieces from it ( a single SSDT or two) and use them with an install done with the older guide that I wrote.
If you have a spare SSD or HDD available try a clean install of Mojave with the 560 installed. Use the above mentioned guide, then you don't have to do all the "house cleaning" and kext updating due to the switch from Nvidia to AMD graphics. It also saves you the time and hassle of cloning your HS install before upgrading to Mojave. Those are the main advantages of a clean install. I'll post a link to his new UEFI hot patch guide when it's completed. As a small preview of how detailed that guide is, here are all the SSDTs that are provided to "hot patch" the ACPI issues to make the 8300 behave more like a real Mac and make future updates go smoothly.
It is all worked out for you. All that is required is that you drag the SSDT.aml into the ACPI/patched folder on the EFI partition. Amazingly simple compared to the extreme level of difficulty it would be to figure this all out on your own.
2. Using the conventional Unibeast/Multibeast methods to move to Mojave
If you want to do an
in place upgrade it saves some time in that you don't have to re-install programs and move data over later. If you choose this then clone your High Sierra system drive first and test that it's bootable on it's own. With either approach you'll need the Clover UEFI 4920 edition provided by Multibeast for Mojave. That is easy enough to accomplish and works fine for Mojave.
How to do the in place upgrade: Create a Mojave UEFI USB installer per the tonymac guide. Boot from that and install Mojave as you would a clean install. Only difference is that you
don't format your HDD as per the standard guide. It then writes the new Mojave files over High Sierra. Keep booting from your Mojave USB until you uninstall the Nvidia drivers and have run Multibeast post install.
The original Sierra Guide didn't use Lilu and Whatevergreen because most everyone was using Nvidia dedicated graphics back then and those kexts were not widely used or required in June 2017. So when you run Multibeast for Mojave you'll want to select AppleALC for audio and Core Graphics Fixup/WEG for graphics support. Those selections will automatically install the Lilu kext as well. Other than that not much is different for Mojave. It's a good idea to run kext utility app after you've run Multibeast to repair permissions and rebuild caches.
The one other thing you'll need is the correct audio layout ID for audio to work. It should be layout id 11. Here's how it should look in CC, Devices/Properties section of the config.plist. Once everything works with your Mojave install you can simply keep using that drive. Save your HS clone as a backup.