GameMode not working with HDMI 2.1 (RTX 3090),Samsung 2020 QLED [1402] Update !!!!!!

[RouDeR]

Background:
TV is 75 inch Q800T (EU version), but I assume this will affect all of the 2020 Samsung TVs
Software is version 1402.6 (updated Octomber 8th)
HDMI Cable 2.1 certified full 48gbps
The same HDMI cable works just fine with HDMI 2.0 GPUs like my old GTX 1080Ti (Game Mode works flawlessly there)
Current GPU:  RTX 3090 with latest Nvidia drivers

What is working as intended when using the HDMI 2.1 port and RTX 3090 as a source::
* Outside of game mode I don't have any problems, I can run at 4k@120hz RGB 10 bit or 8k@60hz 4:2:0 10 bit without any problems.

What does NOT work when using the HDMI 2.1 port and RTX 3090 as a source:
* If you turn on Game Mode, the TV picture goes BLACK and it looses signal
This happens disregarding on what resolution and refreshrate you are playing, I`ve tried the following:
- 1440p@60hz Input Signal Plus ON
- 1440p@60hz Input Signal Plus OFF
- 1440p@120hz Input Signal Plus ON
- 4k@60hz Input Signal Plus ON
- 4k@60hz Input Signal Plus OFF
- 4k@120hz Input Signal Plus ON

- 8k@60hz Input Signal Plus ON
NONE of them was able to switch to Game Mode !!!

However
If the RTX 3090 is connected to one of the HDMI 2.0 ports of the TV, Game Mode is perfectly functional, but then you are restricted to 4k60hz and 8k@30hz

SUMMARY:

Spoiler

Game Mode does not work AT ALL on the HDMI 2.1 port when HDMI 2.1 source is Attached.

[daparky]

https://youtu.be/RBc_qmA3nx4

[jdk2087]

Just a heads up for everyone wondering. The guy who’s testing with the 3080 card is now able to play 4K 120hz with Freesync(VRR) on and no problems. From what I understand he just had to switch to a better HDMI cable. 

[Ultra12]

hello can you sent video how did you do 8k in q800t with nvidia 3090,my nvidia don’t work in 8k only 4K 120 hz.i cliked in nvidia panel 7680×4320 and pc did auto return to 4k

[daparky]

Quick one. 3080 is an NVIDIA card, FreeSync is by AMD, how is this possible?

[RouDeR]

There is a small bug in the Control panel.

Go to the UHD resolutions where 8k is, and select 4k 60hz (below)
Then you should choose advanced color settings > 4:2:0  and 10 bit > apply

Now you can switch to 8k

[RouDeR]

I just updated to 1402.6 (EU)

Game Mode is still completely broken with RTX 3090, what a ***** firmware update...

I`ll upload a video showcase of this piece of ***** compatibility with HDMI 2.1 devices.

[Exoldy]

I finally managed to enable game mode  and 8k resolution (4:2:0), it's really randomly sometimes, but I found a trick,

You need the shortest and without bends cable (I use this one : SIKAI MOSHOU Ultra High Speed HDMI 2.1 Cable 8K 60Hz, 4K 120Hz, 3D Ultra HDR 48Gbps HiFi eARC Dolby Atmos HDCP2.2 HDMI Cable Compatible with Samsung QLED 8K Q900 TV, TCL Roku TV, VIZIO TV (12 Feet))

You need to go to the Nvidia panel, select any resolution and 4: 2: 0 mode, then turn on the game mode, the plus signal automatically turns on, then we will be able to select 8k resolution, but for some reason, there will be no 4: 2: 0 mode, only 4: 4: 4, it cannot be chosen, it will break everything.
so we select 4k resolution and 4: 2: 0 mode, everything will be successful, now we have the opportunity to select 8k resolution and 4: 2: 0 mode, apply and everything works ok.

I tried to activate game mode many times and got either no signal or trying to connect at super low resolution, now I'm guessing it's because of my cable.

Now everything is working stably, but I will try my cable in different positions. Good luck to all.

ps my tv 55 q700t, card 3090 rtx palit 

[Poufy]

Hi, the new Nvidia driver fix the 120hz VRR 4K game mode problem, no freeze, i have the Q800T and RTX 3090. Tested on F1 2020 and Watch Dogs Legion with G-sync activated, it's work perfectly finaly !

[daparky]

What's the picture quality like with VRR enabled?

[Jardo86]

Hi. What cable do you use? I do experience bright flickering when running VRR 4K 120 Hz. I tried several cables including Belkin Ultra HD High Speed 8K HDMI 2.1, but no luck yet...