ubuntu20.04.5，Two graphics cards display，After booting up, the screen only has the mouse。

[346283191]

My hardware configuration is：
CPU：i9-7980XE
MOTHERMOARD：ASUS WS X299 WAGE
GPU：2* ZOTAC RTX 3090

Problem Description：

My first question is：I can already edit the /etc/X11/xorg.conf，Implementing a single graphics card output when I start the machine。
But I can’t realize it. When I switch from the HDMI of the first graphics card to the HDMI output of the second graphics card, by modifying the file, I can only realize that only one graphics card can output at the same system startup. I want to automatic switching.I would like to know how to go about looking for an example of editing the xorg.conf file

My second question is：
When I connect two cards with HDMI to 2 monitors of the same model at the same time，I pass sudo nvidia-setting，Got the following interface。

When I check the settings as follows

After booting up, the screen only has the mouse。

This is my xorg.conf auto generated by nvidia-setting.
xorg.conf (2.6 KB)
nvidia-bug-report.log.gz (563.3 KB)

I’m really looking forward to getting some pointers

[generix]

Please delete xorg.conf and set kernel parameter
nvidia-drm.modeset=1

[346283191]

I didn’t make it clear just now. I know that after deleting the /etc/X11/xorg.conf file through ssh, you can restart and enter the normal system interface, but the problem is that I don’t know how to use the HDMI output of multiple graphics cards. The correct configuration method

[generix]

By setting the kernel parameter, see
https://forums.developer.nvidia.com/t/ubuntu-20-04-not-able-to-run-6-7-monitor-setup-with-one-x-screen/200904/2