Bought this barebone NUC last week, installed Ubuntu 16.04 with two 4GB RAMs, and 120GB SSD, connected with a 50" LED TV via HDMI. Issues encountered below
1. When audio presents via HDMI output, for some time, it's lost, and no longer to see the HDMI audio output selection within the audio control panel, have to restart the NUC to get it back for selection.
2. I have two 2TB removable SATA (same two 2TB WestDigital HDs, each has one primary partition with MBR volume) harddisks connected via the two USB3.0 ports at the back, in rare cases, both can be detected, and for most of the cases, only one USB harddisk can be detected.
I've upgrade the BIOS to the latest version already, any special settings should be there?
I understand that you are currently experiencing Audio and USB problems when using the unit with Ubuntu.
Regarding this, first I would like to inform you that this unit does not support Ubuntu, it is not under the list of supported operating systems therefore there is no microcode available or any kind of update that could be done.
My recommendation up to this point is for you to try to go to a Linux forum and see if they can assist you with the current problem you are experiencing, if possible to test if it is hardware or software problem is to try the unit with Windows*