A:AnswerYou can use HDMI or the Video port which is smaller than the HDMI. the Video port is the best for 4k and only does video the HMDI does 1080p video and also sound.
A:AnswerCheck in the BIOS Setting they maybe turned off.
When you first power on the PC look and it will say BIOS and I believe you hit f12 and it will take you into a old school screen and then navigate thru there and look for the settings and ensure they are on.
if you cant find it or have no idea what I am talking about let me know and I will post pics.