Unticking 'Mirror displays' with disconnected display.

Apr 21, 2017
Gigabyte H170N-WI-FI
Intel® HD Graphics 530
  1. MacBook Pro
Mobile Phone
  1. Android
Hi everyone. My first post on this forum, so I apologise for any mistakes.
So I successfully installed and been using my hack for few weeks now (build in my profile), thanks to your awesome tutorials here.

To the issue:
Where are the mirror / not mirror settings stored on OSX?
I try running Sierra 10.12.4 with dual display setting, but I struggle to get it to work.
After installing 4-port patch it would detect both screens but second screen was black (but could still move windows to it).
Then I tried ticking 'mirror' displays and it started crashing when second screen was connected.
So then I installed AGDPFix and mouse appeared on both screens, but then it started flickering, then primary screen went green and system crashed.
Now it crashes every time I turn on the secondary screen. I have tried different mixture of ports (HDMI > DVI, DVI > HDMI, HDMI > HDMI). Single screen works on HDMI ports, but after installing AGDPFix it worked on DVI > HDMI when I booted on HDMI > HDMI and then switched the cable, but then I tried rebooting and it just crashed when login should appear.

So I have searched a bit through forum and stumbled upon thread where someone was saying that their system crashes on mirroring, but works fine with extended mode. So I hope this would work now.

Target is to get both monitors working in extended mode.
I will appreciate all kind of help.