I actually have this! It was driving me crazy WHY this happened. I do not have a DELL monitor but some AOC Gaming widescreen thing but to make it more weirder:

I actually have this! It was driving me crazy WHY this happened. I do not have a DELL monitor but some AOC Gaming widescreen thing but to make it more weirder: it only occurs when I am using my laptop not my desktop. Both systems are connected using HDMI to the monitor. Only when I am working on my laptop and I have audio over my HDMI cable using my speakers on my monitor and I walk away my monitor blanks and the sounds stops for 5 seconds...