<< Solved >> Hdmi/Displayport hangs osx - will CSM break my dualboot?

[rawbinary]

Hi!

with this guide ( https://www.tonymacx86.com/threads/guide-multibooting-uefi-on-separate-drives.198869/) I have succesfully got Win10 + macOS on seperate SSDs and I am very happy about that!

I have 2 monitors, and so far the only one that macOs will boot with is a Samsung with DVI. If I have my Eizo monitor with displayport or hdmi connected, Mac Os does not boot. But! If I connect HDMI (not displayport) after boot I have dual screen glory! So that is a workaround i guess.

On the other hand it would be great if dual screen worked in both Os without having to remember to unplug for Macos. I have read several places on this forum that multi monitor setups start working when CSM is turned on. Following this guide I currently have CSM turned off because it said to do so after win10 install. So the question is: Will turning CSM on now destroy my macOS installation or do any other harm?

 

[Going Bald]

CSM is Compatibility Support Module for Windows to be able to handle non UEFI platform devices/apps. If you have a UEFI vBIOS on your GPU it should not need CSM enabled.
OTOH, the reason CSM is disabled in the Win10 installation guide is to force the installer to install Win10 in UEFI mode. Once Win10 is installed, CSM can be enabled and should not affect anything.

 

[rawbinary]

ok! thanks for clarifying! It actually worked.. but i had to first set CSM on, then "uefi only" on boot from disk, and "uefi first" on all other items. Now dual screens on gtx1070 gpu working in win+mac!!