As of an update I pulled in on Monday, monitors plugged into HDMI-0 and DP-1 are not detected i.e. they do not show up in the gnome display settings and remain inactive. However they are listed as displays in nvidia-settings.
The odd thing is DP-2 works: it shows up as a display in gnome settings. However, it’s not listed in nvidia-settings.
Before the update, I had all three monitors working with the built-in-display turned off, that is HDMI-0 and DP-1/2 enabled (both DPs with passive adapters).
Rpmfusion switched to render offload mode which makes external monitors connected to the nvidia gpu unavailable. Please see the paragraph
NVIDIA PrimaryGPU Support
on how to revert to the previous behaviour.
I don’t think that’s possible since the PrimaryGPU option is an Xserver feature so the decision has (to) already been made when the driver gets initialized. Furthermore, there are more multi-gpu use cases than this one so it wouldn’t be wise to let a driver decide which gpu is primary. I, for one would be rather annoyed by this.