Section "Monitor"
        Identifier   "Monitor0"
        VendorName   "Monitor Vendor"
        ModelName    "Monitor Model"
        HorizSync    28-88
        VertRefresh  43-71
        Modeline "1600x1200_70.00"  189.50  1600 1664 1856 2160  1200 1201 1204 1250 -hsync +vsync
EndSection

Section "Screen"
...
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes "1600x1200_70.00"
        EndSubSection
EndSection