I have 2 video cards - one in the topmost x16 slot closest to the CPU, and the other connected to the bottom x16 slot (but from an external enclosure connected to a x1 riser card - there was no space to fit another double-slot card here).

Since I updated the BIOS to 4.70 from 3.40, my video card in the topmost slot doesn't display anything on the monitor until Windows loads up (i.e. misses the BIOS screen completely and remains blank even when entering the BIOS after pressing DEL). Instead, it only displays from the video card in the bottom slot, which I don't want to connect to a monitor (because the x1 riser card reduces performance significantly, and also, as it turns out, increases DPC Latency significantly too).

Can we get the motherboard to recognise the video card which is connected to a monitor at boot regardless of which slot it is in? Is this a recognised issue? The behaviour seems to have changed in the later BIOS revisions.

Specs:

Ryzen 1700X, ASRock AM4 B350M Pro4, 2x16GB DDR4, 2 x Gigabyte GTX 1080ti (I know SLI isn't supported - the 2nd card was for another purpose), Windows 10.