When first time connect the mini pc (XBMC with Openelec pre-installed) to TV by HDMI, you should select the correct HDMI devince if it didn’t have any sound. Here is picture guide how to set it:
Step 1: open the Mini HTPC computer and go to its homepage as this picture:
Step 5. Select the right audio output device from the list shows there:
Notice: the above guide suitable for all hystou mini pc like i3-3217u, i5-3315u, i7-4500u and celeron 1037u series mini pcs.