What is GPU?

In plain language

A GPU reads the EDID of everything connected and offers the modes it finds there, including the preferred timing as the recommended resolution. Custom resolutions can be added manually, but the default list is EDID-driven.

Why it matters in your setup

If a mode is missing from the driver's list, the capability data did not describe it — a truncated EDID, a device in between, or a preferred timing that was lost.

GPUs are also sensitive to hot-plug behaviour. TMDS termination on the card can interact with hot-plug signalling in ways that produce odd, hard-to-reproduce symptoms: displays not detected, resolutions changing on their own, outputs not waking.

What the DR HDMI 8K does with it

Firmware 1.2 of the DR HDMI 8K specifically fixed a hot-plug issue on GPUs when TMDS termination is active — a good reason to run current firmware if your source is a PC. Its DTD retention keeps the display's preferred timing intact so the driver does not fall back to a generic mode, and HTPC mode addresses the desktop-rearrangement problem.