Users who combine a GeForce RTX 3080 via HDMI 2.1 with LG OLED TVs from 2019 and 2020 are facing problems. Nvidia’s G-Sync variable refresh rate deployment is not working and CX models are switching to 4:2:2:2 subsampling at 4k120Hz.
The use of the G-Sync Compatible feature on the RTX 3080 video card in combination with LG OLED TVs results in black image. That can be seen in a YouTube video from Tech YES City. Also users on reddit report similar problems. The relevant LG TVs, such as those from the C9 and CX series, are touted as G-Sync Compatible. That’s Nvidia’s name for implementing the HDMI 2.1 feature variable refresh rate. AMD calls it FreeSync.
With this year’s LG CX OLED TVs, gamers can’t get 4k120Hz in view with 4:4:4:4 compression. The TVs automatically switch to 4:2:2 subsampling. HdMI 2.1, in particular, allows viewing at that resolution and frame rate without compression, but users say that’s not currently possible. Also on the Nvidia forum users report that.
With last year’s LG C9 TVs, users can view 4k120Hz with 4:4:4 color coding. Those TVs have an HDMI 2.1 connection with bandwidth of 48Gbit/s, while the CX TVs have a 40Gbit/s connection. However, that should not make a difference. Also, the lower bandwidth of the CX models is enough to display 4k120Hz 4:4:4 at 10bit color depth. In addition, users report that the TVs also switch to 4:2:2 when using an 8bit color depth, which requires even less bandwidth.
Twitter user Sixi82 shows the difference in image quality between 4:4:4 and 4:2:2 and also claims to have tested several HDMI cables, to be able to rule out causing the problems. Presumably, the problems with firmware and driver updates can be fixed. LG and Nvidia have not yet commented on the users’ findings.
View with 4:2:2 subsampling (left) and 4:4:4 view without compression