My Dell Monitor keeps losing signal from my Mac Mini M4 Pro (2024)

My first suspect would be the cable. Modern versions of macOS reportedly do not like to see display transmission errors - and may cut signal if there are such errors. Monitor vendors sometimes bundle “lowest bidder” type cables with their monitors.

A high quality HDMI to HDMI cable, or high quality USB-C to USB-C cable, that supports 4K video, might help here. Try to keep cable length to 3 feet / 1 meter, or less.

REACT-1 wrote:

Is it better to use HDMI than USB?

The advantage of using HDMI is that – as long as you don't care about hooking up the monitor's hub ports, you won't be taking up a rear-panel USB-C / Thunderbolt port that you could be using for connecting other stuff.

The advantage of using USB-C (DisplayPort + USB) is that you can hook up both video and hub ports with one cable. You might also avoid a HDMI 2.0 limitation that means that you cannot have all of (4K resolution, 60 Hz, RGB 4:4:4 encoding, and 10-bit-per-channel color) at the same time.

For the gory details …

Dell – Dell 27 4K USB-C Hub Monitor - P2723QE

Dell – Dell P2723QE Monitor User's Guide

That's a 27" UHD 4K (3840x2160 pixel) monitor with a refresh rate of 60 Hz.

It has a HDMI 2.0 input, a DisplayPort v1.4 input, and a USB-C input that supports DisplayPort v1.4.

It has four USB-A hub ports and an Ethernet port. You can only use them if the USB-C port is connected in some way, e.g.,

• You run a USB-C to USB-C cable from one of your Mac mini's rear-panel USB-C ports to the Dell's USB-C input port. In this case, the USB-C cable would carry both DisplayPort video and USB data.
• You run a HDMI to HDMI cable from the Mac mini to the Dell monitor, and then run a separate USB-C to USB-C cable from one of your Mac mini's front-panel USB-C ports. In this case, the HDMI cable would carry video and the USB-C cable would carry data.

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If you use USB-C to USB-C cable for everything, there is a "USB-C Prioritization" menu (see page 54 of the User's Guide) that controls how much priority to give to USB traffic, at the expense of video traffic. The choices are:

• "High Resolution" – Limits data transfer to USB 2.0 speeds
• "High Data Speed" – Allows data transfer at USB 3.0 speeds, by taking some of the pins that would normally be use for carrying DisplayPort traffic and using them to carry USB 3.0 traffic instead.

Since your monitor supports DisplayPort v1.4, the "High Data Speed" choice would be a reasonable one here. (If I am not mistaken, a 4K monitor that supported DisplayPort v1.2 would be forced to cut back to 30 Hz in "High Data Speed" mode.

For how long is the interruption? 2-3 seconds?

I have an LG 32" 4K monitor w/speakers connected to my M4 Mini by the HDMI cable that came with the monitor and was getting occasional blackouts of 2-3 seconds. There are a number of other users experiencing the same problem. One of them mentioned the app Zoom was the culprit for their blackouts. After removing Zoom they had no more blackouts.

I did have Zoom installed and susbsequently uninstalled it with AppCleaner. I haven't had a blackout since. If you have Zoom installed I suggest you try removing it and all its supporting files.

WARNING: If you use AppCleaner on an app that you have other apps from the same developer, like Adobe, you must be extremely careful checking all checkboxes and deleting.  Some for those files may support other apps from the same developer and deleting them can mess them up.  Adobe apps is a primary example. I know from experience.  For singular apps from a developer it's safe.

If you don't have Zoom installed I suggest you make sure your current cable is securely seated at both ends. If still a problem try a new high quality HDMI cable.