External monitor turning black intermittently

I believe it's most likely a bug in the generic Windows display driver. It's possible you can solve this with a driver from Dell for your display.

I've struggled with exactly that same behavior in one of my monitors, where it randomly goes dark for a couple seconds, then comes back on. The interval between could hours or it could seconds (almost constant flickering.)

In my case, it's two Dell 2405FPW panels side-by-side on my desktop and the problem only presented on my left monitor. Web searches at the time confirmed this a common problem, but seen only on the then-new Windows release I was running and could be traced to Dell having dropped support and not releasing a driver. The random behavior was because I was using the default driver. It drove me nuts for years (but I was too cheap to buy new panels that were supported.) The problem finally (fingers crossed) appears to have gone away a couple months ago with an Nvidia update for my graphics card.

In your case, I don't see others reporting the same behavior with your model and it looks like Dell still supports your monitor. But the behavior you're seeing is exactly what I saw from the default driver. This is why I suspect it may be as simple as downloading the proper driver from Dell.

Good luck. I hope this helps.

I believe it is an HDMI issue as I am having the same problem with a new Vizio 50-inch LED TV. When using HDMI to watch cable tv or Blu-ray discs I get intermittent "no signal" displays where both video and audio disappear for a couple of seconds and then come back. Using component connections I don't have that problem. I don't like using component since the picture quality is not as good, but I can't find a better solution for the time being.