That’s a hardware limitation, current gpus only have 4 display-engines aka heads.
Only way around that are external splitters that pretend to be a 4k monitor and have 4 FHD outputs. Expensive.
Not useful (anymore), see:
https://forums.developer.nvidia.com/t/problem-installing-nvidia-driver-on-red-hat-8-4/195163/9
Forget about this, for two/three/four reasons:
- hardly working on recent Xservers especially with the nvidia drivers
- xinerama and compositing doesn’t work, you are limited to using non-compositing WMs
- GLX might be disabled on one gpu due to being from different generations (Turing+Ampere)
- many things are done in system memory so overall performance isn’t great.
Yes, but nvidia2nvidia prime was only recently added in driver 470 and using nvidia as an output sink still has bugs and performance issues.
Since your 2070 seems be the bottle-neck, please run nvidia-bug-report.sh as root and attach the resulting nvidia-bug-report.log.gz file to your post.
Maybe I can identify some reason.
Outlook: maybe wayland might make this kind of setup easier and reliable, some day.