High Sierra - Z170 Skylake Intel 530 either no acceleration or black screen

[helzayat]

I have the following problem. Whatever settings I use, one of two things happens: either I boot into OS X ok but without acceleration and with About this Mac saying Intel 530 4MB - or I get a black screen about 3/4 of the way into the Apple Logo progress bar. I noticed that there was HD activity after the screen goes black, so I enabled screen sharing and could VNC into the computer from another computer while the screen was black. About this Mac showed the correct 1536MB and acceleration was enabled (Final Cut runs). However there are only two options for resolution: 1280x1024 or 1024x768. My monitor's native resolution is 1366x768. I am using the DB15 VGA connector, not DP or HDMI.
Windows 10 runs perfectly on this computer/monitor combination at 1366x768 by the way.
MB:Gigabyte GA-Z170-D3H
CPU: Core i3 6100 Skylake
No discrete graphics board
16GB DDR4-2400

 

[RehabMan]

I have the following problem. Whatever settings I use, one of two things happens: either I boot into OS X ok but without acceleration and with About this Mac saying Intel 530 4MB - or I get a black screen about 3/4 of the way into the Apple Logo progress bar. I noticed that there was HD activity after the screen goes black, so I enabled screen sharing and could VNC into the computer from another computer while the screen was black. About this Mac showed the correct 1536MB and acceleration was enabled (Final Cut runs). However there are only two options for resolution: 1280x1024 or 1024x768. My monitor's native resolution is 1366x768. I am using the DB15 VGA connector, not DP or HDMI.
Windows 10 runs perfectly on this computer/monitor combination at 1366x768 by the way.
MB:Gigabyte GA-Z170-D3H
CPU: Core i3 6100 Skylake
No discrete graphics board
16GB DDR4-2400

VGA not supported. Use digital connection to monitor (DVI-D, DP, or HDMI).