[sinfulprogeny]

> that the Mac cannot do Display Stream Compression at the Dell's native 6144 x 3456,

Can't, or won't? M1 MacBook pros for some reason can't do 4k120 over hdmi unless you buy a specific usbc-hdmi adapter and fool it into thinking it's displayport (or something like that, I'm paraphrasing. You can find info if you search for cablematters DDC 4k120 m1.)

[wtallis]

There's no "fool it into thinking it's displayport". What you're describing is having the Mac actually literally emit a DisplayPort signal, and a separate device converting that to an HDMI signal. The USB-C HDMI Alt mode standard was never implemented by any real products, and all USB-C to HDMI converters are active adapters that consume DisplayPort signals and emit HDMI signals. Not all of those support HDMI 2.1, which introduced a drastically different signalling mode for HDMI in order to support much higher data rates (and also added display stream compression, further increasing the maximum resolution and refresh rate capabilities).

[thejazzman]

You're missing the point -- you have to use custom firmware on those adapters or Apple still only puts out 4k60

I went deep on this last night shopping for a cable

[brigade]

That "some reason" is that a standard DP-to-HDMI 2.1 protocol converter can't negotiate beyond HDMI 2.0 link rates without the host computer knowing about and doing FRL training on the HDMI side. Completely unrelated to any limitations related to 6144 x 3456.

[lxgr]

Couldn’t the adapter do that?