Raspbian has overscan enabled by default

When I first started up Raspbain on my new Raspberry Pi 2, the picture didn't fill the entire size of the screen. I could see black borders on all sides on my 24 inch BENQ monitor. The reason for this was that Raspbain by default adding overscan to the signal. Modern TVs and monitors don't need overscan and hence disabling overscan altogether can make the Pi graphics fill the entire screen.

Check the settings on TV or monitor first. If this donsn't remove the black borders, then try disabling overscan on the Pi. This can be done by setting the parameter disabe_overscan to 1 in /boot/config.txt and commenting other parameters related to overscan.

1. Take a backup of /boot/config.txt
   sudo cp /boot/config.txt /boot/config.txt.backup
2. Open config.txt for editing
   sudo vi /boot/config.txt
3. Uncomment the #disable_overscan=1 (Remove the #)
4. Comment all other overscan parameters
5. Save and exit
6. Reboot
   sudo reboot