H170M Pro4 simultaneous iGPU and discrete graphics

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   Motherboard: H170M Pro4
CPU: i5-6600
PCIe graphics: RX 580

BIOS settings:
Primary graphics adapter = onboard
Share memory = 128mb (also tried auto)
IGPU multi monitor = enabled

Whatever settings I try, the RX580 discrete graphics seems to become the primary display.  i.e. where uefi bios will appear, if activated, and any os/bootloader screen appears.
I am attempting vifo passthrough of the discrete graphics, and this works only IF I plug a monitor into the rx580 once at ubuntu desktop.  Otherwise, ubuntu kernel attempts to use the discrete card (blacklisted) at boot and the console freezes.  Not locked up, since I can shutdown via ssh.

So,how do I actually make the iGPU the primary graphics adapter when I also have a  PCIe graphics card plugged in to a monitor?
Grateful for any help.

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keeka Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 22 Dec 2015 Status: Offline Points: 30	Post Options Post Reply Quote keeka Report Post Thanks(0) Quote Reply Topic: H170M Pro4 simultaneous iGPU and discrete graphics Posted: 20 Nov 2018 at 6:56am
	Motherboard: H170M Pro4 CPU: i5-6600 PCIe graphics: RX 580 BIOS settings: Primary graphics adapter = onboard Share memory = 128mb (also tried auto) IGPU multi monitor = enabled Whatever settings I try, the RX580 discrete graphics seems to become the primary display. i.e. where uefi bios will appear, if activated, and any os/bootloader screen appears. I am attempting vifo passthrough of the discrete graphics, and this works only IF I plug a monitor into the rx580 once at ubuntu desktop. Otherwise, ubuntu kernel attempts to use the discrete card (blacklisted) at boot and the console freezes. Not locked up, since I can shutdown via ssh. So,how do I actually make the iGPU the primary graphics adapter when I also have a PCIe graphics card plugged in to a monitor? Grateful for any help.

keeka Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 22 Dec 2015 Status: Offline Points: 30	Post Options Post Reply Quote keeka Report Post Thanks(0) Quote Reply Posted: 21 Nov 2018 at 2:54am
	Putting it another way. What is the intended behaviour of this motherboard/uefi when you have a PCIe graphics card as well as onboard graphics enabled AND set primary graphics to 'Onboard'? Shouldn't the UEFI appear on display connected to the intel graphics?