I posted my solution for this problem on page 6 exactly a year ago for Mojave. Now I have the same problem with Catalina.
I was wondering if someone more knowledgable can take a look if I'm doing something obviously wrong regarding me trying to get past the black screen with Asus rx580.
I got it working really well on Mojave with Inject ATI, Orinoco Framebuffer, video ports 5, RadeonDelnit and this kextpatch:
com.apple.driver.AppleGraphicsDevicePolicy BA050000 00 to BA000000 00
Also Lilu and Whatevergreen.
I upgraded to Catalina (got USB installer to boot without black screen by copy/paste EFI from my Mojave install, in the end). Now I boot from USB and it works great, even the clover in the beginning and apple logo is not stretched like it usually is... but booting from SSD results in black screen no matter what I do.
What I tried:
Copying EFI from USB
Latest Lilu and WEG
Checking bios settings, everything is how it should be
Using inject ATI and other before mentioned graphic settings
adding agdpmod=pikera in boot arg
mentioned kextpatch kextpatch: com.apple.driver.AppleGraphicsDevicePolicy
various combinations of disabling inject ATI, disable WEG and/or Lilu and that kext patch
Removing any graphics settings and WEG and/or Lilu
change PEGP to GFX0
changing smbios to 14.2, 17.1, 19.1, iMac Pro 1.1 (This SMBIOS fixed Preview on Mojave)
Enabling/disabling igpu
Tried stabbing in the dark and using some Framebuffer I found while searching
https://github.com/acidanthera/bugtracker/issues/578
I Don't have any DP monitors, so I'm connecting over HDMI. I bought an adapter, but it looks like something is wrong with it because even booting into windows disk with driver and everything I'm not getting anything from any of the DP's on my monitor or tv.
I have an old setup as you can see, and I'm using legacy mode.
Using WEG screen turns off, with inject ATI it stays on but black.
This may be a silly question but I don't know anything, for years I fixed my Hackintosh problems by searching and trying suggested solutions... But anyway If I can boot so well from USB, metal support and both HDMI working... why can't I just apply whatever happens when booting from USB to SSD?
tried copying EFI from USB but that doesn't work either.
Here is my EFI. If There is something more I need to post I would really appreciate if you could mention what tool to use to obtain that info, because after years of using Hackintosh I'm still noob.
Really hope I'm missing something obvious, I have ben trying stuff for days now.