I have two identical external monitors which I have test in windows and they work perfectly with no extra configuration just connect them and done. When I boot to my Debian 8 OS with the three monitor connected all I can see is the mouse moving but that's all(black screens with mouse moving).This is my xrandr output with two monitors:$ xrandr Screen 0: minimum 320 x 200, current 1920 x 2130, maximum 8192 x 8192eDP1 connected primary 1920x1080+0+1050 (normal left inverted right x axis y axis) 382mm x 215mm1920x1080     60.01*+  59.93  1680x1050     59.95    59.88  1600x1024     60.17  1400x1050     59.98  1280x1024     60.02  1440x900      59.89  1280x960      60.00  1360x768      59.80    59.96  1152x864      60.00  1024x768      60.00  800x600       60.32    56.25  640x480       59.94  VGA1 disconnected (normal left inverted right x axis y axis)HDMI1 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 459mm x 296mm1680x1050     59.88*+1280x1024     75.02    60.02  1440x900      74.98    59.90  1280x960      60.00  1280x800      74.93    59.91  1152x864      75.00  1280x720      60.00    50.00    59.94  1024x768      75.08    70.07    60.00  832x624       74.55  800x600       72.19    75.00    60.32    56.25  720x576       50.00  720x480       60.00    59.94  640x480       75.00    72.81    66.67    60.00    59.94  720x400       70.08  As you might see the VGA port is not connected which is the port for my third monitor... My system is a:acer V3-772GNvidia GT 750MCore i7Intel Graphics How to get three monitors to work?
Set up Three monitors in debian
debian;xrandr;multi monitor