- At Highest, over a Thunderbolt cable, the picture isn’t compressed on any Mac. We haven’t measured yet how smoothly older and Intel Macs show it.
- Over Wi‑Fi, Ethernet or USB, the picture is compressed with HEVC. Macs without a hardware HEVC decoder, roughly Intel Macs from before 2017, get H.264, which is limited to 4K: a larger desktop is scaled once to fit.
- A Mac that can’t decode either shows the picture over Thunderbolt only, and the menu says that Network mode isn’t available on it.
- The Mac you work on needs macOS 14 or later, so an older Mac usually becomes the display.
How smooth the picture is on an older Mac depends on that Mac. The speed test recommends what your two Macs can keep up, and Check Smoothness shows what you get. In Settings › Advanced, Encoder can prefer H.264, which suits older Macs.