In plain language
A 60Hz display redraws sixty times a second, a 120Hz display twice as often. Content has its own rate: film is 24 frames per second, television 25 or 30, games anywhere between.
Trouble comes from the mismatch. 24fps film on a 60Hz display does not divide evenly, so frames are repeated unevenly — the slight stutter in slow camera pans known as judder. On a 120Hz display 24 divides cleanly, which is why 120Hz helps with film as well as with games.
Why it matters in your setup
Higher refresh costs bandwidth in direct proportion, which is why 4K120 is such a demanding mode. A display also has to advertise the rate before a source will offer it, and the supported range is part of the capability data — including the VRR window, often something like 40–120Hz.
What the DR HDMI 8K does with it
The DR HDMI 8K reports the frame rate and the VRR range on its OLED alongside resolution and chroma, and its EDID tables let you advertise a specific frame rate rather than leaving it to the chain. If a source refuses to offer 120Hz, comparing the advertised range with what the display actually supports usually settles it in a minute.
Need the hardware?
Open the DR HDMI 8K product page on HDfury.uk.