M2 Mini and intermittent monitor goes black

So after updating to Sonoma 14.1.1, I started having my monitor screen go black for a few seconds. I have a MacMini with the Apple M2 Chip. The strangest thing is, it would be fine and once I stood up from my seat it would go black. Since I don't have any camera installed I knew it wasn't some kind of hack.

I was using a HDMI to HDMI cable. I have now purchased a USB-C to HDMI cable and the problem seems resolved. I did this based on the post from Jame Brickley, thank you James.

It will be interesting to see if Apple ever mentions this was an issue.

USB-C -> DisplayPort is highly recommended over HDMI which is far better suited to televisions than monitors. I found that many monitors with HDMI input do not support all the functionality and perform better with DisplayPort.

As others suggested, check the sleep, energy star settings on the monitor itself as well as macOS.

Same issue, sudden black screen for about 4 seconds while browsing on an M2 Pro Mac Mini running latest Sonoma. Question: If one uses a USB-C to HDMI 2.1 cable, doesn't that mean you give up one of the two USB-C ports? Or can you use it with a cheap splitter/dongle?

Also, this seems like a software issue, since it didn't happen until Sonoma, and why would Apple put an HDMI port if it's unreliable?

Did you check all the power settings? This looks like the monitor is sleeping after a too short amount of time.

System Settings->Lock Screen: Turn display off when inactive for... if it is set to, say, 5 minutes, change it to 1 hour, or whatever you like.

I am using a Belkin HDMI 2.1 High Speed cable between my M2 Mac mini Pro (13.4) and the 32-in LG 4K display. At some point, after the screen saver has run its course, the display will go black to save energy. A click with the Magic Mouse II, or a key on the Magic Keyboard brings the regular screen back in an instant.

I'm not sure yet, but I think your suggestion has solved my problem. After updating to Sonoma 14.4.1 today, my screen would go black every 2-3 minutes for about 4 seconds, then come back on its own without touching keyboard or mouse. I have a M1 Mac Mini with a Dell U3219Q monitor. I even switched from USB-C to HDMI cables and that did nothing. So I checked the Hot Corners option, and somehow the Sonoma update changed my lower-right corner option to "Quick Note", which I've never had turned on before. It's now been in constant use for 3 hours and the screen hasn't gone black yet. I'll post an update if the problem returns, but thanks for the tip!

Sonoma 14.4.1 appears to have reset hot corners to its default where the bottom-right corner is Quick Note. That has been the default since Quick Note was introduced in Monterey. You must have changed the default way back then. Sonoma 14.4.1 also reset my audio device selections back to the default which is not what I normally have configured.

Curious what other settings were reset to factory overriding the users settings...

System Settings->Desktop & Dock, click Hot Corners at the bottom. Maybe one of the corners is set like this:

Get yourself a USB-C to HDMI 2.1 cable instead of using an HDMI to HDMI cable.

One other possibility is that you have a hot corner set up. It pretty easy to accidentally move the cursor and hit a corner and that might be the explanation.

Check the settings for hot corners