I can't get my monitor to set the refresh to 120hz. I'm using an nvidia gtx 970. The outputs are below (I'm using a 120 hz monitor & I was able to set it to 120hz in Ubuntu 15.04 when using an AMD graphics card). Now I am using Ubuntu 14.x and it won't let me set it to 120 hz. Please advise.
$ xrandr
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
DVI-I-0 disconnected (normal left inverted right x axis y axis)
DVI-I-1 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DVI-D-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 521mm x 293mm
1920x1080 60.0*+ 120.0 99.9
1440x900 119.9
1280x1024 120.0 75.0 60.0
1024x768 120.0 75.0 60.0
800x600 120.0 75.0 60.3
640x480 120.0 75.0 59.9
$ xrandr -r 120
Rate 120.0 Hz not available for this size