The ProView AR2238AFJW monitor have 1 VGA and 2 DVI input ports and none of them seems to work correctly to inform Linux to use it's correct native resolution (1680x1050).

If it is connected on HDMI-0 of your GPU card like me, you can place the following lines from Terminal, or create a shell script with them on a "ProView_AR2238AFJW.sh" file.

cvt 1680 1050
xrandr --newmode "1680x1050_60.00"  146.25  1680 1784 1960 2240  1050 1053 1059 1089 -hsync +vsync
xrandr --addmode HDMI-0 "1680x1050_60.00"

Of course, if you connect this monitor to other port, for example, DVI-0, you should change it as follows:

cvt 1680 1050
xrandr --newmode "1680x1050_60.00"  146.25  1680 1784 1960 2240  1050 1053 1059 1089 -hsync +vsync
xrandr --addmode DVI-0 "1680x1050_60.00"