Gaming HDMI trouble tends to look alike: a grayed-out 120Hz option, VRR that disappears once an AV receiver joins the chain, or a picture that falls back to 60Hz. EDID is not always to blame, but it is how the source learns what sits downstream, so check it first.
Two EDIDs, side by side
The web server MAIN section lists the EDID of the sink at the output (EDID TX) next to the EDID the source reads at the input (EDID RX), each with video formats, video capabilities and audio formats. On the unit, the OLED RX EDID page shows maximum resolution, frame rate, color depth, chroma, bandwidth and whether VRR and ALLM are enabled; the TX EDID page gives the sink's details. Comparing them reveals where a capability goes missing.
Checking a 4K120 chain step by step
- Make sure RX and TX are both reported as connected.
- Look at EDID TX to confirm the display advertises 4K120 and VRR in the first place.
- Load a predefined 4K120 table: 17–19 are 4:4:4 10-bit FRL-5 with VRR, 23–25 are 4:2:0 with VRR.
- If the picture drops out, lower the maximum FRL rate or turn VRR or ALLM off in modify mode, one change at a time.
- Restart the source after each EDID change so it reads the new capabilities.
What the VRR and ALLM flags actually do
In [COPY TX SINK EDID and MODIFY] mode, VRR and ALLM are on/off switches layered over the sink's own EDID. Turning one off shows whether that feature is linked to a black screen or an unexpected mode change. The flags only alter the advertisement; real VRR operation still depends on the source and display.
Among the predefined tables, VRR appears only in the 8K60 group (11–13) and the 4K120 groups (17–19 and 23–25). Among the ten custom-default slots, #4 (Q9FN ALLM VRR HDR10+) names VRR, and slots copied from HDMI 2.1 TVs such as the LG C9 and C1 may carry it as well. There are no 4K60 tables with VRR.
Cable quality at 120Hz
The manual calls for a certified or tested 1500MHz cable for a full 48Gbps link. A cable that is almost good enough can pass for an EDID fault: the source selects 4K120 because the EDID allows it, and the link then fails to hold that rate.
Frequently asked questions
Can I switch VRR and ALLM on or off?
Yes. Both are on/off video flags in the copy-and-modify EDID mode, applied on top of the EDID copied from your display.
Which predefined EDID tables include 4K120?
Tables 17–28. Numbers 17–22 are 4:4:4 10-bit FRL-5 and 23–28 are 4:2:0. In each group the first three include VRR, all include HDR, and each comes in 7.1, 5.1 and 2.0 audio versions.
Does advertising 4K120 make a 60Hz TV accept 4K120?
No. The EDID only changes what the source is offered. The display and the cables still have to handle the signal.
Where to buy
The DR HDMI 8K is available from HDFury.eu.