[Mojave] Use iGPU through GTX 1050 port(s)?

I've switched to my integrated HD630 graphics (on my Core i7-7700 CPU) to upgrade to Mojave. My Dell Inspiron 3668's Intel H110 motherboard only has one HDMI port, and one VGA port (which I've been told macOS no longer supports). Previously, I had a dual screen setup using the HDMI and DVI-D ports on my GTX 1050.

Is it possible to either:

- Continue using the HDMI + DVI-D ports on my GTX 1050, but keep using the iGPU, or

- Use the HDMI port from the motherboard and the DVI-D port from the GTX 1050? (My UEFI settings seem to allow this.)

When I try the first option, the verbose mode boot log shows on the HDMI screen up (the DVI-D screen receives no signal) until the point where the Apple logo should show. At that point, the HDMI screen also receives no signal.

When I try the second option, booting in verbose mode, the DVI-D screen shows the text from booting up until the row of white plus signs, and then stays that way. With verbose mode disabled, it stays blank.

HDMI (right) plugged into the motherboard, and DVI-D (left) plugged into the GTX 1050

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My graphics properties:

Graphics properties

Is what I'm trying to achieve impossible, or am I doing something wrong?