andre@andre-System-Product-Name:~$ cvt 1680 1050 60
# 1680x1050 59.95 Hz (CVT 1.76MA) hsync: 65.29 kHz; pclk: 146.25 MHz
Modeline "1680x1050_60.00" 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync
andre@andre-System-Product-Name:~$ xrandr --newmode "1680x1050_60.00" 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync
andre@andre-System-Product-Name:~$ xrandr --addmode DVI_I-0 "1680x1050_60.00"
xrandr: cannot find output "DVI_I-0"
andre@andre-System-Product-Name:~$ xrandr --addmode DVI-I-0 "1680x1050_60.00"
andre@andre-System-Product-Name:~$ xrandr --addmode DVI-I-0 "1680x1050_60.00"
X Error of failed request: BadMatch (invalid parameter attributes)
Major opcode of failed request: 140 (RANDR)
Minor opcode of failed request: 18 (RRAddOutputMode)
Serial number of failed request: 31
Current serial number in output stream: 3
andre@andre-System-Product-Name:~$ xrandr --output DVI-I-0 --mode "1680x1050_60.00"
xrandr: cannot find mode 1680x1050_60.00
andre@andre-System-Product-Name:~$ xrandr --output DVI-I-0 --mode 1024x768 --rate 60
root@andre-System-Product-Name:/home/andre# xrandr --size 1680x1050
Size 1680x1050 not found in available modes
root@andre-System-Product-Name:/home/andre# xrandr --size 1680x1050
Size 1680x1050 not found in available modes