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

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.

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.

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.

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.

<< 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?

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.

that is why I was fishing for what the 'system information' panes were reporting --

to help determine whether slow or erroneous ThunderBolt response or slow or uncertain display response might be the underlying cause.

since you did not specify, I have to ask,

Are you using the ports on the back of the Mac Studio?

any additional displays involved?

That would be a better workaround but unfortunately it doesn't work.

Thanks. I will give those suggestions a try while I’m waiting for apple to fix this.

when do we expect apple to fix this issue ?

its happening on mac studio m5 max as well.

restarting the mac studio helps temporarily but the issue re-appears