Ultra HDMI 2.1 Optical cable that works with an NVIDIA RTX 3080 and 3090 and LG OLED B9 and C9 at 120hz 4K 4:4:4 VRR

It’s been a painful road to finally find a working optical cable between a graphic card RTX 3080 / 3090 and an LG OLED B9 and C9 TV. When I say working; it has to be working at 4K 120hz 4:4:4 (RGB) 12bits HDR VRR (Variable Refresh Rate) or 8K 60hz.

Like many of you, I like to play some games in front of my couch with the finest graphics and like you, my computer is in another room. My computer is in my office and I need at least 25 feet to run a cable around the walls so it also looks good. The problem?

Ultra HDMI 2.1 cables (and above) use copper and are limited to 5 meters (15 feet) in the best case scenario if you are lucky. This limitation has been resolved by some crackpots engineers and figured out a way to convert the HDMI signal to light and light to back to HDMI signal using optical cables with no visible lag. But there is a catch!

To convert the signal to lights (optic), engineers needed a chip and that one needed to be compatible / compliant with HMDI specifications and this has to be correct for both the sources and the displays. Many constructors didn’t follow that specifications and released TVs and devices with chips that were supposed to follow the “HDMI 2.1” standards and some promising upcoming release of firmware fixes to enable full 2.1 bandwidth. LG is no exception.

There are two ways to achieve 4k 120hz : uncompressed (4 lanes of 12gbps = 48 gbps)) data or compressed data. As you can imagine, the first uses the entire bandwidth. In these lanes, there aren’t just video data passing, but also hand shake (HDCP) for security protection and EDID which basically indicates all supported resolutions (including the native one) of the TV to the source. This is where some HDMI 2.1 chip (like Panasonic) makers failed and constructors used them and resulted in black screen between some equipments. And wait, LG even released their “X” OLED Series CX and BX with only 40gbps that didn’t even follow their previous generation standard. You read it right!

So now we are with many “un-standards” Ultra HDMI 2.1 if you want to give it that name. Like the COVID, we now have variants of Ultra HDMI. Example, you could have your XBOX Series X or you PS5 that works with your receiver to your TV no problem and have your RTX 3080 to the receiver to the TV with no picture at all or your RTX to your TV that works right off the bat. Confusing? Well, we are in a limbo and all in this together! When there is a problem what do we do? We find a solution. Well, that one was hard to find! We now have a company (RUIPRO) on Amazon.com that figured that out and that is offering the correct version based on your equipment. This isn’t cheap though and there is a process follow!

You got to use Amazon.com, choose the length (I am using a 50ft) of the cable, buy it and immediately contact the vendor with your specifications. You tell the vendor that you have an LG OLED C9 (same for B9, I have tested both) and your graphic card (ex: ASUS TUF 3080). They will come back to you and tell you that the product they will send is the GEN 3 version B of this optical cable. It will ship from China but shipping is fast (under a week).

I have tried around 5 optical cables before I realized they were all not gonna work until someone program the chips to decode and encode properly for the LG Series 9.

Please be aware that optical cables are one way, so you will have to look at both end (source and display) before you run the cable.