Apple Studio Display 120 Hz not detected by Mac Studio on boot

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Level 1

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Apple Studio Display 120 Hz not detected by Mac Studio on boot

I have an M4 Max Mac Studio running macOS 26.7 with a single Apple Studio Display XDR on the supplied Thunderbolt 5 cable. The Studio monitor has the latest offered firmware. On most warm or cold boots macOS detects the display at 60 Hz and does not offer 120 Hz at all. Disconnecting and reconnecting the Thunderbolt cable at the display immediately causes 120 Hz/Adaptive 120 Hz to become available. I reproduced the same behavior with both Adaptive 120 Hz and fixed 120 Hz. I previously experienced essentially the same maximum-refresh-rate negotiation problem with an LG high-refresh monitor on this same Mac. Is this a known issue?

Posted on Sep 23, 2026 5:36 PM

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Answer 1

tschiro Author

Level 1

4 points

Sep 24, 2026 7:48 PM in response to Grant Bennet-Alder

This appears to be a known issue requiring a software fix. In the meantime, one workaround is to unplug the monitor for a few seconds then plug back in. Another workaround is to unplug the Thunderbolt cable from the monitor while the computer is running, then plug back in.

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Answer 2

Sep 25, 2026 1:14 PM in response to tschiro

That works because...

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 3

tschiro Author

Level 1

4 points

Sep 25, 2026 12:28 PM in response to den.thed

That actually seems to work. When I tried it before I was too quick to reawaken. If I let it sleep for 30 seconds or more, it resets the refresh rate to 120 Hz once I wake it up. Much better than removing cables. Thanks for the suggestion.

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Answer 4

den.thed

Level 10

97,882 points

Sep 24, 2026 8:02 PM in response to tschiro

That is a terrible work around, because it causes a lot of unnecessary ware on the ports and cable connectors.

What I would do is test a Hot Corner set to Display Sleep and then a re-wake or Sleep from drop down menu and re-wake instead of wareing out the ports and cable.

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Answer 5

Sep 24, 2026 6:35 AM in response to tschiro

<< the USB-C cable that came with the Studio Monitor XDR. >>

The cable for connecting the display should be clearly marked with the ThunderBolt symbol on each end. It needs to be a Thunderbolt 5 PRO cable or an ACTVE Thunderbolt 5 cable to maintain 120 Hz connection.

could it be defective?

Option-Apple Menu > system Information > Graphics & Displays ...

what shows for display information? (its text so it can be copied and pasted here)

what shows for Thunderbolt to the Display?

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Answer 6

tschiro Author

Level 1

4 points

Sep 23, 2026 7:47 PM in response to Grant Bennet-Alder

I am using the USB-C cable that came with the Studio Monitor XDR and connecting to the appropriate port on the back of the Mac Studio. No other displays or peripherals are connected to the Mac Studio. Seems like a handshake issue as sometimes it boots with Adaptive 120 hz enabled.

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