2020 75" Q90T HDMI 2.1 with NVIDIA RTX 3080/3090 Flicker & Disconnects

[99xexp]

Hey everyone.

I wanted to know if anyone else is experiencing problems with achieving 4k 120hz + HDR with the new RTX graphics cards on the current Q80T/Q90T models.

With number of feedbacks from a small community on Nvidia including myself, we noticed that enabling Input Signal Plus (or so called HDMI UHD Color) in order to use VRR on Game Mode results in an unstable, flickering state and will not work properly.

As a reference, it looks something like this: https://www.youtube.com/watch?v=RBc_qmA3nx4&feature=youtu.be

We have tested rigorously through the past week trying out tens of HDMI cables (we know they're not "Certified" HDMI 2.1, but are advertised as Ultra High Speed HDMI with 48gbps output), different resolution+refresh rate settings, and with the last two known updates to Samsung TV firmware (1302, 1402.1) as well. Nvidia also released two driver updates so far however, the problem doesn't seem to resolve at all.

Interestingly, Input Signal Plus on other ports besides Port 4 (hdmi 2.1) works perfectly as they should, whether it's connected via hdmi 2.0b or hdmi 2.1 cable (limited bandwidth by the port anyways), with maximum setting of 4k60hz + HDR on 4:2:2 subsampling. The problem occurs as such in the above mentioned video ONLY when Input Signal Plus is enabled for Port 4. You cannot set the resolution higher than 4k60hz without that setting.

After numerous attempts at different cable lengths and models, PSU swaps (6pin+6pin on different source), and gathering reports from the community with verified issue on all Samsung TVs, we are inclined to believe that it's likely a firmware / support issue on Samsung QLED and its proper HDMI 2.1 support.

LG CX/C9 also had a similar issue (G-Sync related) but was followed up by their team and was resolved with a firmware update to the LG TVs.

I reached out to Samsung via Twitter but was simply told to let Nvidia know lol. Not very helpful so far.

If anyone else here have had a similar experience or resolved it on your own, we would love to hear it from you.

Thanks!

Edit 10/15/2020:

We are aware that the user manual on the TV's only list 2560x1440@120hz or 4k@60hz for VRR as officially supported resolution and refresh rate. However the issue is persistent even when VRR is disabled both either via Game Mode (TV Setting) or Nvidia Control Panel.

tl;dr Port 4 currently has issues even for hdmi 2.1 bandwidth usage.

[useryop2lhdtIz]

Thanks for starting this discussion! Same happening to me: RTX 3080 on 55" Q80T. I got that Zeskit cable on Amazon, and things seemed to work great for a week. Then, I started getting flickering and screen blanking when running 4K at 120 Hz + HDR. For now, I've kept my refresh rate to 60 Hz + HDR, and things have stabilized.

Another issue I'm having is that, if I'm turning on the TV for the first time in about an hour, I can't switch to my PC on HDMI 4 immediately. I found that switching to another input (e.g. the cable box on port 1) and then toggling Input Signal Plus off and on for HDMI port 4 then allows me to switch to my PC. Saves me getting up to unplug the cable, at least.

edit: Also on firmware version 1402.1 and latest Geforce driver

[userIZJMpp129T]

How can you update to 1402? I am on 1301 or something and it says it's the latest update. 

[useryop2lhdtIz]

I followed the instructions under firmware > see more at the link below:

https://www.samsung.com/us/support/owners/product/qled-tv-q80t-2020

[userFO1OJGwZjh]

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@useryop2lhdtIz wrote:

Thanks for starting this discussion! Same happening to me: RTX 3080 on 55" Q80T. I got that Zeskit cable on Amazon, and things seemed to work great for a week. Then, I started getting flickering and screen blanking when running 4K at 120 Hz + HDR. For now, I've kept my refresh rate to 60 Hz + HDR, and things have stabilized.

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Is the issue present when you are using 4k @ 120hz but without HDR ?

[useryop2lhdtIz]

I had a different flickering with 4K @ 120 Hz with no HDR. Got brief black-and-white flickers, and no black screening (i.e., temporary signal loss). With HDR on, the flickers were rainbow colored, and occasional signal loss.

I also tried dropping the refresh rate to 100 Hz but had the same issues.

[userFO1OJGwZjh]

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@useryop2lhdtIz wrote:

I had a different flickering with 4K @ 120 Hz with no HDR. Got brief black-and-white flickers, and no black screening (i.e., temporary signal loud e). With HDR on, the flickers were rainbow colored, and no signal loss.

I also tried dropping the refresh rate to 100 Hz but had the same issues.

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😞

I am getting my HDMI 2.1 cable today and both my RTX 3090 and Samsung Q80T are ready, I am so worried now :(.

Did you have the Game Mode enabled or disabled when you experienced the issues ?

[useryop2lhdtIz]

Game Mode is disabled. When I first got the TV, I tried enabling Game Mode, but it created another interesting issue: when I tried switching away from PC to my cable box, and it gave me a message like "the resolution is not supported. please change the resolution on the device", meaning the cable box. The only way around that was to unplug my PC's HDMI cable, so I haven't enabled Game Mode since.

[userFO1OJGwZjh]

I got my HDMI 2.1 cable today and went to test everything.

I was able to get 4k @ 120hz, 10 bit, and GSync enabled. No issues at all. My specs: Gigabyte RTX 3090 Gaming OC, drivers: 456.71, Windows 10 Pro x64 (with all updates), Samsung Q80T with 1402 firmware, Savio CL-143 HDMI v 2.1 Cable 3m. In TV settings I have Input Signal Plus enabled on HDMI 4. I hope I am not praising the day before sunset.

Have tested both in games and in Windows, no issues.

That's what somebody else wrote about the issue on YouTube:

 "Well, I was able to get everything working at 4k 120Hz with VRR and HDR enabled, so I'm happy. They key is to turn on the TV before turning on the PC - no sync issues in that case."

I always turn my TV first, then the PC, so I am not sure if I would have experienced any issues if I had turned the PC first and then the TV.

[userIZJMpp129T]

The flickering doesn't happen in the bios or loading screen into windows. So could this be a problem with windows itself?

Another hdmi2.1 cable came today, and this still has the problem so...

[99xexp]

@userIZJMpp129T I think most users are on 2004 Windows 10, but myself is using Windows 10 LTSC on 1809. Similar / same issue still.

Although I get more of those random flashes of jumbled color than a flicker, but a problem regardless. And yup, almost all consumer grade cables don't seem to do much atm.