Monitor Disconnecting from Mac Studio M3 Ultra

Question

Monitor Disconnecting from Mac Studio M3 Ultra

Hi All,

I'm having a bit of a problem with my 2025 Mac Studio M3 Ultra. This is paired with a Samsung LS49DG954SUXUU 49" OLED.

After a bit of bother getting it to connect and display the correct resolution (the answer was a DP to USB C) it all looks and works fantastic, that is until the display disconnects from the Mac. The only happens when watching a video, or at the end of a slice when using Lychee slicer, and it does not happen every time. The latter is a large part of my business.

It's becoming a little bothersome, as to get the Mac to talk to the monitor again I have to disconnect the DP cable, then reconnect.

I've turned off the option to send the monitor to sleep both at the monitor end, and the Mac end, but still the problem persists. This has happened with two different cables of different brands.

The Mac is a week old and bang up to date on updates, the monitor a couple of days old and the same, so if anyone has encountered this before any help would be much apprciated.

Mac Studio, macOS 15.5

Posted on May 16, 2025 1:29 PM

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Answer 1

May 16, 2025 2:03 PM in response to TheGrumpyBadger

Punchline:

Recent versions of MacOS will disconnect a display that incurs any errors during transmission of display data.

That display appears to be a 5K wide display with HDR 10 bits/color (with the bottom half missing).

As such it must mostly meet the timing constraints of a 5K display, but has a little bit of wiggle-room because there is less data overall.

I am not sure how you arrived at ANY solution that involved a USB connection, because according to standard tables, reliable operation over USB-C or anything converted from USB-C is limited to 30 Hz at 10 bits/color OR 8 bits/color.

If you were to acquire a certified HDMI cable that meets the ULTRA (8K at 60Hz) specification, and connect it directly, from your 2023 or later Mac Studio to display, standard timing says 60Hz is rock solid and resolutions up to 120 Hz may be possible. You would get generally get FAR better, more reliable results with this display.

The other one-cable alternative would be to obtain a genuine Thunderbolt adapter to DisplayPort, but these generally are only found built into Thunderbolt docking stations, likely because they draw too much power.

there are also some two-cable alternatives if you would like to explore those.

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Answer 2

May 16, 2025 4:21 PM in response to TheGrumpyBadger

When you have a really outrageously huge display, you sometimes find that you can't feed it all the data you want with one cable. So you run it with two, each of which is now perfectly happy to carry less data than the total stream required.

What you effectively do on the Mac is set up the left and right sides as separate displays, run with separate cables. Then use the Mac arrange pane to place the left and right halves next to each other.

In the display, you use Picture-By-Picture (cousin of Picture-In-Picture) feature to place the two halves back together.

Users report it works well with no dividing lines, no mismatched updates, no compromises.

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Answer 3

May 16, 2025 3:01 PM in response to Grant Bennet-Alder

Sir, thank you so much for your answer. I'll give the HDMI a go. Believe it ot not, it runs WOW at 120hz fine and dandy. It really is just video playback (it's an F1 weekend, so it's on at one side) and when the print files we gener ate finalise that this crops up.

Sorry to be a pain, but being absent from Apple for the past decade or so, would you be able to elaborate on the two cable approch?

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Answer 4

May 16, 2025 4:25 PM in response to Grant Bennet-Alder

You're a diamond, thank you so much.

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