I have 2 Asus R7-370's graphic cards (not attached at present) in addition to my onboard Intel graphics in my Asus Prime Z390-A setup.
When I install the 2 (likely cross-fired) R7 cards, how should I set the following UEFI parameters? (note, I've attached my Speccy text file)
Allows you to select a primary display from CPU, PCIE and PCI graphical devices.
Primary Display [Auto]
Allows you to select the primary display from CPU, PCIE and PCI graphics devices.
Configuration options: [Auto] [CPU Graphics] [PCIE] [PCI]
iGPU Multi-Monitor [Disabled]
This item allows you to empower both integrated and discrete graphics devices for the
multi-monitor output. The CPU graphics shared system memory size is fixed at 64 MB.
Configuration options: [Disabled] [Enabled]
RC6(Render Standby) [Enabled]
Allows you to enable or disable render standby support. Configuration options:
DVMT Pre-Allocated [64M]
Allows you to select the DVMT 5.0 pre-allocated (fixed) graphics memory size used by
the internal graphics device. Configuration options: [32M] [64M] [96M] [128M] [160M]
[192M] [224M] [256M] [288M] [320M] 
Also, I have 2 displays. Both are attached at present to the onboard graphics, one with a Displayport cable, the other with an HDMI cable. Any suggestions as to the best way to set up this combination of equipment if and when I install the 2 graphic cards?
ISAAC.txt 114.52KB 61 downloads
Extraneous background: I've been having a hardware/software nightmare since early November. I essentially rebuilt my entire setup, clean installed Win 10 4 times now, etc.,etc. A week ago, everything was working very smoothly for 5 days when I tried installing the graphics cards. I kept the output hooked to the onboard graphics, everything was fine. When I switched the cables to the R7 cards and changed the UEFI settings, everything cratered, BSOD's, endless "Windows repairing" notes ..... Grrrrr! I won't bore you further, but this is getting to my 76 yr old psyche.