The TL;DR is that the organization that controls the HDMI standard won’t allow any open source implementation of HDMI 2.1.
So the hardware is fully capable of it, but they’ll get in trouble if them officially implement it.
Instead it’s officially HDMI 2 (which maxes out at 4k @ 60Hz), but through a technique called chroma sub-sampling they’ve been able to raise that up to 4k @ 120Hz.
However there are some minor reductions in picture quality because of this, and the whole thing would be much easier if the HDMI forum would be more consumer friendly.
In the meantime, the Steam Machine also has display port as a completely issue free display option.
I really wish I could find a TV within my desired specs that had DisplayPort. We will buy a Steam Machine to use it in place of our docked Steam Deck in the living room, so being able to use DP would be amazing.
Adapting DisplayPort to HDMI with minimal quality loss is child’s play. It’s the other way around that’s misery.
Any cheap adapter cable that supports DisplayPort In to HDMI Out should be perfectly fine.
i want to say you can buy an adapter to get dp 1.4 out of steam machine and into hdmi 2.1 on a tv and should be fine. just has to be a powered adapter i believe
The powered adapters are for the other way around. DP has support for HDMI out without additional components, but ofc the HDMI forum makes converting HDMI to DP like pulling teeth.