Resolved: DVI to VGA adapter, didn't work anymore in High Sierra. Connected display via Displayport - everything works. Hi guys, I have a cMP 4.1, flashed to 5.1, that I ultimately want to upgrade to Mojave. But I am kind of stuck currently. So here's what I did: 1. Acquire cMP 4.1, already flashed to 5.1 (MP51.0084.B00) - check. 2. Acquire Gigabyte Radeon HD 7950 and flash it with the modified firmware provided in this thread - check. Beautiful bootscreen, everything looks fine. 3. Make a fresh install of Sierra from USB to a new HDD - check. HD 7950 works without any issues. 4. Obtain and run the full installer for High Sierra (10.13.6) in order to upgrade firmware to MP51.0089.B00 - check. Firmware update worked just as expected. 5. Proceed with installing High Sierra 10.13.6 - check. Actually, this is where the trouble began. During the installation, the screen went black, seems like High Sierra didn't like the 7950, but the installation obviously completed successfully nevertheless (just let the updater do its thing for a while although I couldn't see any GUI). And here's the current situation: - Start up with only the HD 7950: Screen goes black after reaching about 3/4 of the startup progress bar, where the login screen should be. - Start up with the HD 7950 AND the original GT 120 (with the display connected to the latter): works fine, boots into High Sierra normally, both cards show up in the system report. Obviously I am not able to install Mojave since the installer requires all installed GPUs to be Metal capable. So the rest of the plan looked like this: 6. Obtain full installer of Mojave using Mojave Patcher - check. 7. Install Mojave - not there yet. I am aware that certain displays are known to cause trouble (DP 1.2 / 4K) so I used an old 19" TFT connected via DVI-VGA adapter. So as I said in the beginning, I am kind of stuck, actually. Extensive googling didn't really turn up any real solution. Any help would be appreciated! Edit: The problem doesn't seem to be uncommon. See here and here (in German). So it might have something to do with the AMD graphics driver in High Sierra. But it seems that the dosdude1 High Sierra Patcher contains an "AMD GPU Patch". Still have to figure out whether this patch can be installed on my existing HS installation or whether I have to create a USB installer and start over.