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 have a HDMI splitter, like a 5 input 1 output thing. I have not used it in awhile. Does HDMI pass through the DRM or is the DRM in the splitter?
The source device (the steam machine in this case) will check with the display and see what the highest HDMI standard they both support is. It may also check if your splitter supports it, but I suspect the splitter is just a passthrough device.
I figured. I also used the wrong term, it is a switch.
I know some HDMI switches will, some won’t and others will strip the DRM and let the picture go through. I had to try several ones to get a conference room TV to work with a HDMI auto switch. Funny it was the cheaper model on Amazon lol