Mac Studio with M3 Ultra and Studio Display XDR at 120 Hz

This is a user-to-user forum. You'll need to check with Apple if you want an official answer.

That said, my guess is "Probably."

The Technical Specifications for that Mac do not promise support for 120 Hz refresh rates (See: Mac Studio (2025) - Tech Specs – Apple Support), but they indicate that it supports Thunderbolt 5. Thunderbolt 5 can support much higher video bandwidth than Thunderbolt 3 and 4.

The Technical Specifications for the Studio Display XDR (Studio Display XDR – Tech Specs) would appear to imply that it supports 120 Hz on many Apple Silicon Macs running macOS Tahoe 26.3.1 or later.

It does seem likely that a Studio Display XDR would use up two of the M3 Mac Ultra's eight display generators – in much the same way as an 8K, 60 Hz or 4K, 240 Hz display would. That Mac can drive as many as 8 of the original 5K, 60 Hz Studio Displays; but it might only be able to drive four Studio Display XDRs.

You should be able to get at least 80 Hz, by some calculations I was able to run.