ERROR: The control display is undefined; please run `nvidia-settings --help` for usage information

I try to overclock the NVIDIA graphics card on Linux, there will be errors when using nvidia-settings, When I run nvidia-settings -t -q GPUUtilization on Linux I get this error:

Unable to init server: Could not connect: Connection refused

ERROR: The control display is undefined; please run `nvidia-settings --help` for usage information.

I tried almost everything I could find, but still reported the same error.

And here is my xorg.conf.

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

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "ModeValidation" "NoDFPNativeResolutionCheck"
    Option         "ConnectedMonitor" "DFP-0"
    Option         "CustomEDID" "DFP-0:/etc/X11/dfp0.edid"

Thanks for any suggestions.