Recently I was juggling around running VNC on my Ubuntu. I needed a specific resolution to be maintained and was figuring , how to do it. After some time of googling and doing some research I wsa able to get the solution .So the steps are pretty simple.
Open your terminal and time the following command
cvt 1280 710 60 ( here you can give what resolution you want, 1st and 2nd argument are resolution ,whereas 3rd argument is the refresh rate frequency in Hz)
karthik@karthik-virtual-machine:~$ cvt 1280 710 60
# 1280×710 59.85 Hz (CVT) hsync: 44.17 kHz; pclk: 73.50 MHz
Modeline “1280x710_60.00” 73.50 1280 1344 1472 1664 710 713 723 738 -hsync +vsync
Next copy the above line except “Modeline keyword” and paste it in the terminal with xrandr prefix
karthik@karthik-virtual-machine:~$ xrandr –newmode “1280x710_60.00” 73.50 1280 1344 1472 1664 710 713 723 738 -hsync +vsync
karthik@karthik-virtual-machine:~$ xrandr –addmode Virtual1 “1280x710_60.00”
Enter the above command. Note that I have used a keyword “Virtual1” which could be different in your system.
Just type xrandr and see what is “connected” to the device. That name would be your device name.
Have fun !