Sometimes you just want 1680x1050, and Nvidia just won't give it to you. This still requires an `xrandr -s 1680x1050` after login with nvidia-331...

xorg.conf

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
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"
    HorizSync       30.0 - 81.0
    VertRefresh     60.0
    Option         "DPMS"
    Option         "ExactModeTimingsDVI" "TRUE"
    Modeline       "1680x1050_60.00"  146.25  1680 1784 1960 2240  1050 1053 1059 1089 -hsync +vsync
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    Option         "ModeValidation" "NoEdidModes"
    Option         "ConnectedMonitor" "DFP"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "MetaModes" "1680x1050_60.00 +0+0; nvidia-auto-select +0+0"
    Option         "nvidiaXineramaInfoOrder" "DFP-0"
    SubSection     "Display"
        Depth       24
        Modes      "1680x1050_60.00"
    EndSubSection
EndSection