No display after logging in when i change to device1 in screen section of xorg.conf in dual nvidia gpu

Graphics / Linux Linux
1

I have a system with 3060 and 1660 both connected to same display via different hdmi ports, i would like to switch to 1660 for display tasks and leave 3060 for cuda like here,

The following is xorg.conf and /etc/X11/mhwd.d/nvidia.conf i changed after reading the above link. the following file works i can get display on 3060

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "LG Electronics LG TV"
    HorizSync       30.0 - 135.0
    VertRefresh     24.0 - 120.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "NVIDIA GeForce RTX 3060"
EndSection

Section "Device"
    Identifier     "Device1"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "NVIDIA GeForce GTX 1660"
    Option         "AllowEmptyInitialConfiguration"
    BusID          "PCI:4:0:0"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0" # changing to device1 here changes screen but goes blank after login
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "metamodes" "nvidia-auto-select +0+0"
    Option         "SLI" "Off"
    Option         "MultiGPU" "on"
    Option         "BaseMosaic" "off"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

but when i change the screen section to device1 for switching, the screen successfully switches to other gpu and hdmi port and i can see the login screen and can enter the password too, but after pressing enter after kde logo and gear wheel the display goes blank/black and the display starts displaying no signal.
I think my file is missing some config. please help.
the bug report is
nvidia-bug-report.log.gz (760.4 KB)

Thanks in advance.