LG CX OLED Issues with NVIDIA GeForce RTX 3080 GPUs: Forced Chroma Subsampling, Broken G-SYNC

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Update – 9/22/2020 – NVIDIA has let us know that the below issue will be resolved with a firmware update that LG will roll out to its customers.

If you’re thinking of pairing NVIDIA’s new flagship graphics card with one of LG’s CX Class OLED TVs, you may be in for a sub-optimal display experience. Users on AVS Forum, HardForum, and reddit are complaining about forced chroma subsampling in 4K/120 Hz mode, whereby uncompressed 4:4:4 signals are being delivered in 4:2:2. That’s a little odd for a display with HDMI 2.1 ports rated for 40 Gbps of bandwidth.

Our friends at rtings.com have a nice article on the technicalities behind chroma subsampling, but what this basically means is that users are getting a lower-quality picture. While the effects of chroma subsampling are negligible with certain content (e.g., movies and television shows), the degradation can be pretty obvious in static images, particularly those that contain text on top of flat colors. It can look like a blurry mess at times.

We’re guessing that this is an issue on LG’s side, as the NVIDIA GeForce RTX 3080 doesn’t exhibit this problem with other televisions. Let’s hope that a software fix is coming soon. Apparently, there’s G-SYNC issues, too.

You can check out some comparisons between 4K/60 Hz and 4K/120 Hz on an LG CX OLED/NVIDIA GeForce RTX 3080 setup below, courtesy of AVS Forum’s Sixi82. Notice the smeared text in the salmon and blue rows in the bottom gallery? Yep, that’s the nastiness of chroma subsampling at work.

LG CX OLED + NVIDIA GeForce RTX 3080 in 4K/60 Hz Mode

LG CX OLED + NVIDIA GeForce RTX 3080 in 4K/120 Hz Mode

Tsing Mui
News poster at The FPS Review.

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