Black screen with multiple monitors when CSM is disabled (High Sierra+NVIDIA)

I got a good deal on a 4K monitor and decided to switch my home workstation from Linux to MacOS for better HiDPI support.

Installation went fine, everything worked until I plugged my old 1920x1200 monitor to use as a secondary vertical display. With both screens plugged in, the 4K display would be used for Clover and the text console, then (when going into Graphical mode) the second (vertical) screen would switch on to a black screen and the 4K monitor went into standby mode. Either monitor by itself worked fine, but one of the DVI ports (DVI-D, the one without extra pins for analog output) didn't work at all.

This was extremely frustrating, I tried various combinations of Dual Link, VRAM, Inject NVidia, BootDisplay and Video Ports in my Clover config, but none of that worked. I was about to give up and switch back to Linux, when after A LOT of googling I found a post on tonymacx86 suggesting enabling CSM in UEFI. After doing that, I finally got output on both monitors.

Other than this very minor gripe (and being stuck on High Sierra thanks to the NVIDIA GPU), my installation is perfect. I'm mostly sharing this, so that if somebody experiences the same issue, it's easier for them to google.

I'm still slightly curious what could be causing this. It's not like Clover is actually booting in CSM mode. If you do know the solution that would let me disable CSM for the slightly faster boot time, please let me know.

The same display setup worked fine on Linux with CSM disabled.

Specs:

  • CPU: Intel Core i7-4790k @ 4.6GHz
  • Motherboard: ASUS Z97M-PLUS
  • Storage: Kingston 128GB SSD
  • GPU: ASUS Strix Nvidia GTX 970 with NVIDIA Web Drivers - Outputs: 1xDisplayPort, 1xHDMI, 1xDVI-I, 1xDVI-D
  • OS: MacOS High Sierra 10.13.6
  • WiFi: TP-LINK TL-WDN4800
  • Bluetooth: IOGEAR GBU521
  • Monitors: Acer 27" 4K IPS (DisplayPort, scaling set to Looks like 3008x1692) + Dell 24" 1200x1920 IPS (DVI-I)
  • Clover version: 4741 "UNIBOOT X" repack from a Polish hackintosh forum
  • Kexts (probably could get rid of some of these): AppleALC (Inject 20), AtherosE2200Ethernet, FakeSMC_CPUSensors, FakeSMC_GPUSensors, FakeSMC_LPCSensors, FakeSMC_SMMSensors, FakeSMC, IntelMausiEthernet, Lilu, RealtekRTL8111, SATA_Legacy, USBInjectAll, WhateverGreen, Z97LPC
submitted by /u/killing_garfield
[link] [comments]