What is HTPC?

In plain language

A home theatre PC feeds a television or projector like any other source, but it behaves like a desktop: it has a resolution list, a colour format setting, a refresh rate setting, and opinions about which display is primary.

Why it matters in your setup

Two problems come up repeatedly. The desktop rearrangement: turn the display off and Windows moves everything to another screen, and turning it back on does not undo it. And colour format: a PC benefits from RGB or 4:4:4 for text, which many televisions only accept on specific inputs with a specific setting enabled.

Graphics drivers also have their own quirks, including TMDS termination behaviour that can interact badly with hot-plug events.

What the DR HDMI 8K does with it

The DR HDMI 8K has an HTPC mode for exactly the first problem, keeping the PC seeing a display when the real one sleeps — noting that HTPC mode is not compatible with HDCP. Its EDID tables include explicit RGB and 4:4:4 entries for the second, and firmware 1.2 fixed a hot-plug issue on GPUs when TMDS termination is active.