Using the AB350 Minit ITX board, which only has HDMI out.  Have it connected via HDMI to an Asus PB277Q (2K) monitor.  When the monitor sleeps, the system starts giving "Device Disconnect" and "Device Connect" sounds every few seconds, in that order.

I know that there is some wonkiness with HDMI and various forms of low power states, and that sometimes an HDMI connection doesn't send the low power state correctly to the display.  

Anyone else experiencing anything like this?  I rummage through the BIOS to see if there was any reference to HDMI or power state, but nothing I could find.  Also, there's something in Radeon  settings called "HDMI Link Assurance" which I tried but that doesn't seem to fix it either.