Ubuntu 14.04 Unknown Display

Solution 1:

I found this on the Arch Distro BBS maybe it can help: Intel HD Graphics 4600 driver works as Intel Xeon E3-1200

You might try installing the Intel-microcode package as well. You are most likely utilizing the Intel Processor's GPU, without knowing what model Mother Board you have.

Solution 2:

This might help someone.

Try a better VGA cable.

A poor quality VGA cable often causes this kind of problem. I've recently stumbled upon this strange problem and couldn't able to find a reasonable cause for this issue in Ubuntu (In 16.04.2 for me).

Cable type which worked for me : HOTRON E246588 AWM style 20276 VW-1 80°C 30V