I assure you that it is an HDMI in. I own the Alienware 14 (no HDMI in) and the Alienware 18 (HDMI in) I can hook an hdmi cable from the 14 to the 18 and hit FN + F9 and my Alienware 18 will display what is on my Alienware 14 screen. I assume it can be done with any other HDMI source as well.