I have an RX480 that came in Dell XPS and I've noticed during normal use, not gaming at all, just surfing the web, working on a word document, just about anything, it will go to a black screen for about 4 or 5 seconds, then it will just come right back up. It goes totally black, no error messages, no restarts, no codes.
I have tried several monitors, now I am using a 1080P 32" Samsung TV and it is still happening. Switched from my 4k monitor. I am using a top of the line Monster Cable Gold HDMI cable, and have tried others as well.
Radeon Software Version - 18.3.4
Radeon Software Edition - Adrenalin
Graphics Chipset - AMD Radeon (TM) RX 480
Memory Size - 8192 MB
Memory Type - GDDR5
Core Clock - 1266 MHz
Windows Version - Windows 10 (64 bit)
System Memory - 24 GB
CPU Type - Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz