High-definition has been the staple of the gaming industry since the Xbox 360 was released in 2005. Microsoft's white and green console ushered in the HD craze with ample cables and multiple resolution settings. One of those cables is the HDMI, which is the highest quality HD cable offered for the console. Once the cable is connected to your console and TV, all you have to do is set your resolution on the Xbox 360.
Turn off your console and connect the HDMI output to your Xbox 360's HDMI plug-in. It is labelled on the back of your console.
Disconnect any other A/V cable from your console if necessary.
Connect the other end of the HDMI cable to your TV's HDMI input.
Turn on your console and go to the dashboard.
Locate My Xbox then scroll right to "System Settings" and select it.
Select "Console Settings," "Display" then "HDTV Settings."
Select "Optimal" to allow your Xbox 360 to automatically determine and set the highest resolution.