@WhosMac @SpikedBR @heyelly
I've just installed Catalina successfully using only the iGPU, as follows:
Phase 1:
- Start with the USB install disk you created by following the Catalina Mini-Guide.
- Connect it to your Mac.
- Now, in the ZIP attached below there are two config.plist files:
- config-Internal-GPU.plist
- config-AMD-GPU.plist
- We will perform the installation with the Internal file and then switch to the AMD-GPU file later.
- Copy config-Internal-GPU.plist to the CLOVER folder of the USB install disk.
- Open the file with Clover Configurator, go to SMBIOS section, and select iMac19,1 from the pop-up menu.
- Save the file and then rename it to simply config.plist.
Phase 2:
- Power down, flip power switch on PSU to OFF, then completely remove the RX 5700 XT GPU from the system.
- Don't skip any one of these steps.
- Connect HDMI cable to rear IO panel and to your monitor.
- Don't use a TV. Use a computer monitor.
- Power up the system and press Del to enter BIOS Setup.
- Change Initial Display Output to IGFX.
- Save and quit.
- Press F12 at BIOS Splash Screen to open BIOS Boot Menu.
- Select the USB install disk.
- At the Clover Boot Menu, select the leftmost icon (the external USB disk).
- Follow the on-screen progress.
- When the installer starts, run Disk Utility and format the target disk as APFS, select the Scheme as GUID Partition Map, and give it the name Catalina
- You must select View --> Show All Devices... and click on the parent name of your target macOS SSD. Then click Erase and you will see three options: Name, Format, and Scheme.
- Then quit Disk Utility and select the option to Install macOS.
- When the system reboots, make sure to press F12 at BIOS Splash Screen.
- Select the USB install disk.
- At the Clover Boot Menu, select Boot macOS Install from macOS Catalina
- NOTE: We will NOT select the USB install disk in Clover Boot Menu any longer. We will still use the USB disk to boot the system because only the USB disk contains the EFI partition that allows computer to boot.
- The macOS installer should automatically resume and take 15-30 minutes.
- When it reboots, press F12 again and select the USB install disk.
- At the Clover Boot Menu, select Boot macOS from macOS Catalina
- Now you will be greeted with the Welcome screen.
- Follow the wizard. You can login to iCloud or do it later.
- When you're at the desktop, run Clover Configurator to Mount EFI partitions of both the USB install disk and the new Catalina SSD.
- Copy the entire EFI Folder from EFI partition of USB disk to EFI partition of Catalina SSD.
- Eject the USB install disk.
- Reboot and see if Catalina starts up.
Phase 3: Prepare to install RX 5700 XT.
- (Steps to be provided later.)
- Do not do this yet.
- Please report your progress with Phases 1 and 2.
Voodoo Science: For some reason
System Information --> Graphics/Displays is showing 4K at 60Hz when connecting my Asus Designo 4K monitor to the on-board HDMI port. This port should
not support 60Hz. I'll post screenshot later this evening if I can prove to myself that I wasn't hallucinating. Maybe it's a bug in 10.15.1, but the screen did not flicker when moving windows around as it does at 30Hz. Anyway, this could just be a mistake on my part. But if the 3 of you have 4K monitors, see if you also get 60Hz.
View attachment 439031