There are a few possible solutions for this issue.
Change Scaling on Display settings.
Use the graphics adapter software to change the “Scaling” option to adjust the display size. Intel, AMD and NVidia use different software to accomplish this so please refer the video card user guide for detailed information.
Change Aspect Ratio on projector.
Open the Menu for the projector, go to Settings>Aspect Ratio and change the setting to Auto.
Change Overscan setting on monitor.
Some monitors have an overscan setting, to change it please do the following: Press “1” button on the monitor, go to Manual Image Adjust, Overscan, Press “1” to check the box then press “2” to exit.