Dell U3225QE display cycles connection with Mac Mini M4

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Level 1

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Dell U3225QE display cycles connection with Mac Mini M4

New Dell U3225QE display suddenly losing and regaining connection to my Mac Mini M4. Purchased this a few weeks ago. I have it connected via HDMI. Everything running fine. Occasionally, when starting up from sleep, it would take a few taps of the keyboard or mouse to wake up the display.

Today, it started cycling through: Mac Desktop->Black Screen->Dell logo (like when you first power it on)->Black Screen->Mac Desktop with window showing the type of connection, resolution and refresh rate (5 seconds)->Black Screen.

I did recently update to the latest Tahoe 26.4.1, but this start happening many days after the upgrade.

iPhone 16 Pro, iOS 26

Posted on Apr 24, 2026 8:20 AM

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Answer 1

Top-ranking reply

Grant Bennet-Alder

Level 10

142,981 points

Apr 24, 2026 8:43 AM in response to Johnny S.

that Dell U3225QE appear to be a 3840 by 2160 (4K) display at 10 bits/color, with refresh rates from 48 to 120 Hz.

Interfaces include:

HDMI 2.1

ThunderBolt-4 with (optional) up to 140 W power delivery.

if you are attempting to connect to a MAC with the HDMI cable "shipped the box" you are making an error in judgement. Such cables are often "lowest bidder" cables, and are NOT adequate for high end displays unless labeled as certified AND:

HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"PREMIUM High Speed HDMI cable" or that + "with Ethernet" (up to 4K at 30Hz) --OR--

“ULTRA High Speed HDMI cable" or that + "48G" (supports higher resolutions and backward-compatible)

Cables with No Certification tags are good for your standard 720p TV set, and not much more.

Cables 'shipped in the box' with many displays can be "lowest bidder" cables that are not up to high-end display use. Cables with no markings 'found' behind your TV set are unlikely to be good enough.

HDMI was invented for HD TV sets. it works great at its original resolution of 720i or 720p. At higher resolutions, it quickly develops issues that are complex to solve, and the cables and adapters required to solve are NOT intuitive.

For this use you will need ULTRA Certified cables.

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Answer 2

Johnny S. Author

Level 1

18 points

Apr 25, 2026 4:10 AM in response to Johnny S.

The Ultra HDMI cable arrived, I used it to test the monitor and the problem persists. The logic has been:

Dell: HDMI-to-MacMini - started failing after 2.5 weeks

Dell: HDMI-to-Macbook - not working

Dell: Thuderbolt-4.0-toMacMini - not working

Ultra HDMI-to-MacMini - not working

Ultra HDMI-to-Macbook - not working

Dell: HDMI-to-Macbook - working

Ultra HDMI-to-Macbook - working

I also noticed that the simple power button wasn't working. The back of this Dell monitor only has two buttons. There is the on/off and there is a simple "joystick" that you push to get the menu and then the joystick you use to maneuver around.

If the on/off button isn't working, then the Dell display itself is failing.

Sending it back for the refund. I may or may not get it as it is a "storefront" in Amazon. Haven't had good refund experiences with those stores.

Thanks for the suggestions. I typed out all my experiences so someone googling might see what else to try.

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Answer 3

Apr 24, 2026 10:29 AM in response to Johnny S.

Seeing the Thunderbolt symbol (Lightning with a tiny arrow on one end) is encouraging. That says the cable is certified, the only way they allow that symbol to be used.. Check for max 0.5 meters length as well.

Some displays have On-Screen Display settings that can be used to tell the display a computer is attached on a certain port, or a certain port should be highest priority. Changing those may make your display more responsive.

--------

The Mac does not rely on Windows-like side-loaded "Drivers" which are actually packages of resolutions and settings for a specific display. Instead, it goes straight to the immutable source -- it asks the display itself.

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)

so try doing some of those things and see if the display comes alive.

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Answer 4

Apr 24, 2026 8:44 AM in response to Johnny S.

if you choose to connect with a Thunderbolt cable, that will allow the use of the Hub devices on the display as well, However:

Brand-X ThunderBolt-3 or -4 cables for this use are limited to 0.5 meters maximum. Longer lengths require the use of ACTIVE or PRO level cables that contain Signal Re-Drivers, and typically start at around US125.

ThunderBolt-5 cables are slightly more costly, but provide no additional speed unless ALL devices are ThunderBolt-5 devices and it switches to Thunderbolt-5 transmission signaling.

if your Mac mini does not actively REQUEST (optional) USB Power Delivery over ThunderBolt, it will not be supplied by the display. No damage to anything will be done in any case.

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Answer 5

Johnny S. Author

Level 1

18 points

Apr 24, 2026 9:03 AM in response to Grant Bennet-Alder

Thank you very much for responding. Here's a longer recounting of what happened.

I purchased this display at the beginning of April
It is delivered, I unbox it and I first try to connect it with the Thunderbolt-4 cable they shipped with it. Verified that both ends have the lightning bolt stamped on the ends.
When connecting the display, the Dell screen kept saying, "No Thunderbolt-4 cable detected" There are A LOT of connectors on the back of this display
I get fed up and just defaulted to the HDMI cable I had been using in my last display
Everything worked and I was running for about 3 weeks now
Until the reconnect cycle started up today
Run a two-display 2-mac setup
I reset the HDMI cables, still cycling
I swapped HDMI cables between my mac mini and my company macbook. the Dell system is cycling still when connected to the macbook
I pulled the Dell display and put on an old HP system (running 60Hz) with the same old HDMI cables and everything is stable
Reading your response about older cables on newer systems, I gave the thunderbolt cable that came with the system another look
I realized that when I first got the system, I was plugging the TB cable into one connection off (wrong) on the back of the Dell.
I plugged it into the correct connector and the "No TB-4 cable found" message goes away
And the disconnect-reconnect cycle continues on

I'm in the computer biz and worked customer support in the past. So I know the different permutations to try. So, I'll have to go buy a top end HDMI cable off of Amazon and give it a try. And if that doesn't work, then the Dell display is a lemon and I've got 4 days to return it.

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Answer 6

Apr 25, 2026 8:27 AM in response to Johnny S.

<< I typed out all my experiences so someone googling might see what else to try. >>

THANK YOU for doing that!

This discussion will be here for a long time, and others will find it by searching. Your additional information and what you did to solve your problem will help them think about their issues more deeply and hopefully, provide a solution or encourage the asking of another question.

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