this is the output of #xrandr:

bash-4.3# xrandr
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 640 x 480, current 1280 x 1024, maximum 1280 x 1024
default connected 1280x1024+0+0 0mm x 0mm
   1280x1024      0.00*
   1024x768       0.00
   800x600        0.00
   640x480        0.00
1680x1050 (0x7d) 241.500MHz
        h: width 2560 start 2600 end 2632 total 2720 skew    0 clock 88.79KHz
        v: height 1440 start 1443 end 1448 total 1481           clock 59.95Hz

how could I set the resolution to 1680x1050 . I have formely tried by installing the nvidia driver, but after a while the mouse and kbd usb stopped functioning again. I fixed the problem by removing nvidia. this time the mouse and kbd are functioning perfectely well. so I would like to have a better resolution (1680x1050) without nvidia driver.