Second monitor detected but not working

I have a PC with Ubuntu 22 and a NVIDIA graphic card. When I plug the second monitor, it is detected but it stays black. The Xorg log show:

[ 54734.333] (EE) [drm] Failed to open DRM device forpci:0000:05:00.0: -2

[ 54734.333] Number of created screens does not match number of detected devices. Configuration failed.

[ 54734.333](EE) Server terminated with error (2). Closing log file.

This is the output of nvidia-smi:

This is the content of /etc/X11/xorg.conf:

Section "ServerLayout"    Identifier     "Layout0"    Screen      0  "Screen0"    Screen      1  "Screen1" RightOf "Screen0"    InputDevice    "Keyboard0" "CoreKeyboard"    InputDevice    "Mouse0" "CorePointer"EndSectionSection "Files"    ModulePath "/usr/lib/xorg/modules"    FontPath   "/usr/share/fonts/X11/misc"    FontPath   "/usr/share/fonts/X11/cyrillic"    FontPath   "/usr/share/fonts/X11/100dpi/:unscaled"    FontPath   "/usr/share/fonts/X11/75dpi/:unscaled"    FontPath   "/usr/share/fonts/X11/Type1"    FontPath   "/usr/share/fonts/X11/100dpi"    FontPath   "/usr/share/fonts/X11/75dpi"    FontPath   "built-ins"EndSectionSection "Module"    Load  "glx"EndSectionSection "InputDevice"    Identifier  "Keyboard0"    Driver      "kbd"EndSectionSection "InputDevice"    Identifier  "Mouse0"    Driver      "mouse"    Option      "Protocol" "auto"    Option      "Device" "/dev/input/mice"    Option      "ZAxisMapping" "4 5 6 7"EndSectionSection "Monitor"    Identifier "Monitor0"    VendorName "Monitor Vendor"    ModelName  "Monitor Model"    HorizSync  30.0 - 83.0    VertRefresh 50.0 - 75.0EndSectionSection "Monitor"    Identifier "Monitor1"    VendorName "Monitor Vendor"    ModelName  "Monitor Model"    HorizSync  30.0 - 83.0    VertRefresh 50.0 - 75.0EndSectionSection "Device"    Identifier  "Device0"    Driver      "nvidia"    BusID       "PCI:5:0:0"    Option      "SLI" "Off"    Option      "MultiGPU" "Off"    Option      "BaseMosaic" "on"EndSectionSection "Screen"    Identifier "Screen0"    Device     "Device0"    Monitor    "Monitor0"    DefaultDepth 24    SubSection "Display"        Depth     24        Modes    "1920x1080"    EndSubSectionEndSectionSection "Screen"    Identifier "Screen1"    Device     "Device0"    Monitor    "Monitor1"    DefaultDepth 24    SubSection "Display"        Depth     24        Modes    "1920x1080"    EndSubSectionEndSection

This is the output of xrandr:

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767HDMI-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 598mm x 336mm   1920x1080     60.00*+  59.94    50.00     1680x1050     59.95     1600x900      60.00     1440x900      59.89     1280x1024     60.02     1280x800      59.81     1280x720      60.00    59.94    50.00     1024x768      70.07    60.00     800x600       72.19    60.32    56.25     720x576       50.00     720x480       59.94     640x480       72.81    59.94  DP-0 disconnected (normal left inverted right x axis y axis)DP-1 disconnected (normal left inverted right x axis y axis)DP-2 disconnected (normal left inverted right x axis y axis)DP-3 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 598mm x 336mm   1920x1080     60.00*+  59.94    50.00     1680x1050     59.95     1600x900      60.00     1440x900      59.89     1280x1024     60.02     1280x800      59.81     1280x720      60.00    59.94    50.00     1024x768      70.07    60.00     800x600       72.19    60.32    56.25     720x576       50.00     720x480       59.94     640x480       72.81    59.94  DP-4 disconnected (normal left inverted right x axis y axis)DP-5 disconnected (normal left inverted right x axis y axis)

Notice: if I try to run xrandr --output HDMI-0 --auto --primary --output DP-3 --auto --right-of HDMI-0, I only see the HDMI monitor (as usual), with all the active windows missing and the DP monitor staying black.

How can I fix this problem?

EDIT: the Xorg log says

Using config file: "/root/xorg.conf.new"

but this file does not exist.