Black screen with my RX480 when trying to boot USB 10.13 Installer disk

[apfelwurm]

Hello!
I am now on 10.12 Sierra and I would never touch this systems as it works 98% ok
However using the usual USB disk preparation with Uni- Multibeast I would like to try a test install of 10.13 on my 2.HD.
No matter what I configure for that USB I never get to the installer as the boot from the USB disk ends up in a black screen and an apparent freeze. I can follow the verbose boot log until a certain point when the screen turns black.
As I have a working installation on my 1.HD I copied over my current 10.12 clover config as well as most of the needed kext over to the USB drive:

1. into /EFI/clover/kext/other
2. into /L/E manually on the USB drive

Lilu Kext is at V1.3.4, WhateverGreen at V1.2.6 I intentionally did not update the kext as Hight Sierra is not the lastest OS.

I do aim to get the Installer running without IGPU as this never worked on my Hacintosh. The RX480 is otherwise just fine.

Any hints were to go from here?

 

[apfelwurm]

Got it solved by myself: you got to use the HDMI Port instead of DP! Then screen turns black at boot but readjust itself some seconds later.
-> successful install of OSX 10.13 on my 2.HD