I just install ubuntu 18.04 in a new computer this is my firts time with Linux.

i want to send audio signal to my sound bar via digital cable but linux seems not to see the realteak audio from my mother board, it just sees the HDMI from my gpu. i already uninstall and re install the audio drivers. when i go to the terminal and use alsa mixer it just show me the gpu driver.

my MB it is a TRX40-AORUS-PRO-WIFI with a threadripper 3960x processor.

what can i do about this?