4k,120hz + G-Synch over 30 meters - HDMI optical does not behave!

[Cryptic645]

Hi there,

 

I would like to connect my gaming system from the office room with the tv from the living room. In perspective, the cable should be hidden in the wall, hence the necessary length of 30 meters. For this I tried somewhat expensive cable from Jenving (SUPRA - HDMI 2.1 AOC (optical) 8k/HDR 30 Meter cable).

 

The components used for testing always had the latest firmware or driver version.

LG OLED 77 C9PLA, Firmware 05.00.10

Gigabyte NVIDA RTX 3080 Gaming OC, 461.09

 

Within the HDMI 2.1 specification I intend to run 3840x2160p in 10 bit + VRR /G-Synch over the 30 meters distance. Unfortunately, I cannot operate the components with the 30 meters Supra cable (but it works with a cheapo 3 meter Hdmi cable).

 

I tried several settings with the 30-meter super cable, of which the following settings worked:

1920x1080p @ 120 hz, RGB 10 bit

1920x1080p @ 120 hz, RGB 12 bit

2560x1440p @ 60 hz RGB, 8 Bit, G-Synch

3840x2160p @ 60 hz, 4:4:4 with G-Synch – 8 bit

3840x2160p @ 60 hz, 4:2:0 with G-Synch – 10 bit

3840x2160p @ 50 hz, RGB with G-Synch – 8 bit

3840x2160p @ 30 hz RGB - no G-Synch - 10 bit

 

The following settings did not work with the 30 meters Supra cable:

3840x2160p @ 50 hz, RGB with G-Synch – 10 bit

3840x2160p @ 60 hz, 4:4:4 G-Synch – 10 bit (screen flickers rarely for one second before going black) 

3840x2160p @ 60 hz, 4:4:4 no G-Synch – 10 bit

3840x2160p @ 60 hz, 4:2:2 no G-Synch – 8 bit

3840x2160p @ 100 hz, 4:2:0 no G-Synch 8 bit

3840x2160p @ 120 hz, 4:2:0 no G-Synch 8 bit

3840x2160p @ 120 hz, 4:2:0 with G-Synch 8 bit

 

Variance of testing:

All tests have been made with and without LGs Instant Gaming Response / VRR / G-Synch and with and without LGs Ultra HD Deep Color enabling option.

I tested the cable in the rolled-in state as well as in the unrolled state, in case there should be any differences. Kinks or other damage are not visible.

 

When I applied the desired settings (3840x2160p @ 120 hz, 10 bit RGB) for the first time with the Supra cable, the TV flickered for several seconds and the picture appeared partly. After that, the picture was no longer displayed. In subsequent attempts, the flickering never occurred again, the picture remained permanently black for those settings. Only the previously listed settings work reliably.

 

The settings that were the most closely aligned with the desired target, using the Supra cable were:

3840x2160p @ 60 hz, 4:4:4 with G-Synch – 8 bit

Interestingly for 3840x2160p @ 60 hz, 4:4:4 with G-Synch –10 bit  the picture flickers for 1 second and then the screen goes black sometimes.

 

For reference, a no name HDMI 2.1 cable in 3 meters I got from Amazon for 16 € works at the following desired settings.

3840x2160p @ 120 hz, 10 bit RGB with working G-Synch

I assume that it also works for outputs with a lower bandwidth.

All components support DSC (if necessary?)

 

For the record, both the graphics card and the TV support HDMI 2.1 and the supra cable was used in the correct orientation. No other devices were connected to the TV while testing. Multiple HDMI ports of the devices were used during testing, although every single port supports HDMI 2.1 at 48 Gbit/s.

 

The Supra cable requires a voltage of 5 volts from the HDMI port for operation. So far, I could not find any data whether the RTX 3080 also provides this. I wonder if a too low output voltage means that only the signals with a high bandwidth are not transmitted.

 

Does anyone have a tip or approach to this?

[Stahlmann]

There is a widespread compatibility issue with RTX 3000 GPUs using HDMI 2.1 optical cables. Sadly i had the exact same issue where i couldn't get any optical cables to work at full bandwidth, but 3m copper cables worked without any issues. Most cable manufacturers know about it and most amazon sites selling 2.1 optical HDMI cables specifically state there are issues with RTX 3000 GPUs. I've tried 10 or so different "2.1 marketed" optical cables and not a single one worked at 4K 120Hz. I've almost gone crazy myself trying to figure this out. The highest i got to work with any cable was 4K 60Hz 4:2:2 10-bit, which is basically the HDMI 2.0b spec.

 

Currently i'm waiting for this one to arrive as a 10m variant: Optical Fiber HDMI 2.1 Cable Ultra-HD 8K@60Hz 4K@120Hz for RTX 3080/RTX3090/PS5 | eBay

This is the first OPTICAL cable i found that specifically states compatibility with RTX 3000 GPUs.

[Inrix]

On 1/20/2021 at 4:46 AM, Stahlmann said:

There is a widespread compatibility issue with RTX 3000 GPUs using HDMI 2.1 optical cables. Sadly i had the exact same issue where i couldn't get any optical cables to work at full bandwidth, but 3m copper cables worked without any issues. Most cable manufacturers know about it and most amazon sites selling 2.1 optical HDMI cables specifically state there are issues with RTX 3000 GPUs. I've tried 10 or so different "2.1 marketed" optical cables and not a single one worked at 4K 120Hz. I've almost gone crazy myself trying to figure this out. The highest i got to work with any cable was 4K 60Hz 4:2:2 10-bit, which is basically the HDMI 2.0b spec.

 

Currently i'm waiting for this one to arrive as a 10m variant: Optical Fiber HDMI 2.1 Cable Ultra-HD 8K@60Hz 4K@120Hz for RTX 3080/RTX3090/PS5 | eBay

This is the first OPTICAL cable i found that specifically states compatibility with RTX 3000 GPUs.

Hey did you get it to work? I'm currently trying to find a fiber optic cable that can handle 4k120hz over 20m but am also running into the same issues... 

[Stahlmann]

15 hours ago, Inrix said:

Hey did you get it to work? I'm currently trying to find a fiber optic cable that can handle 4k120hz over 20m but am also running into the same issues... 

The one i posted actually works. I get some occational image dropouts every now and then (sometimes after a few minutes, sometimes after a few hours). But they only last 1 second or so and the sound keeps playing. Otherwise this one works with a 10m cable for me. But i'll probably buy a "certified" cable to get rid of the last small issues once they're available for this lenght. (If there will ever be one)...

[Inrix]

19 minutes ago, Stahlmann said:

The one i posted actually works. I get some occational image dropouts every now and then (sometimes after a few minutes, sometimes after a few hours). But they only last 1 second or so and the sound keeps playing. Otherwise this one works with a 10m cable for me. But i'll probably buy a "certified" cable to get rid of the last small issues once they're available for this lenght. (If there will ever be one)...

OMG Thanks so much! I'll definitely try getting one and post here how it goes then. So annoying finding ones that work