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.

[userZX93pu5U7J]

I reported the issue (VRR bright flickering) to Samsung UK suport. I advise to report the issue to everyone so Samsung recognize there is a problem and they start work on it (I hope I am not the only one at the moment). So far, the issue is still there after last 1403 update.

[uservjkMC3vuVA]

Firmware 1403.1 is out on the Samsung website.  Does that fix any of these issues?  I can't test it myself as I can't install FW from the US region on my Australian Q950TS and it is not yet available via a TV update.

[empythreedom]

I'm not sure I want to beta test this!  I wonder if there is a way to downgrade the firmware.  I did not download a copy of 1402 just in case.  Does anyone have a copy of 1402 for Q90T Canada before I test 1403?

[uservjkMC3vuVA]

I have a copy of the 1402 firmware, but I don't think there is any way to downgrade, at least not for consumers

[empythreedom]

After the update, while I was looking for anything that had changed.  A minute or two into it, there was the opportunity to click on details when it said "update complete" or something to that effect.  I missed the opportunity to select "details" before it vanished.  Hopefully someone else will take note of what that message details.

There are now notes in the e-guide about "Read Before Connecting a Computer (Supported Resolutions).   I am uncertain if they existed before.

[useryop2lhdtIz]

Well, spoke too soon, hah. Couple days ago, I could not switch to HDMI 4 again. Because Game Mode had been turned on, I was also not able to toggle Input Signal Plus to get video output to work. I had to unplug the HDMI cable and plug it back in. I have turned off Game Mode since.

Today, I started noticing some flickering again, that random colorful flashing. It's less frequent then before, though, and sometimes I can see a whole feature-length film without flicker.

I can still switch to HDMI 4 without toggling Input Signal Plus, so long as Game Mode is never enabled. I will try the new firmware sometime soon and see if that helps stabilize things, as I really want to be able to use Game Mode again. The variable refresh rate made games look a lot smoother.

[userhB3VN0ihC7]

Alright so after some experimentation its working nice.

To get the tv to sync with windows on startup I have game mode set to AUTO.

I leave the TV off, power on the PC, as soon as I hear the start of the first long beep for the no vga warning from the bios I turn the TV on.

From there on it's all good.

If i turn on the tv before the pc, or for any time after the  beeps I have to reset or unplug to get it to sync.

Hope this helps someone.

[userZX93pu5U7J]

Do you have bright flickering issue when using VRR? For more users (including me) it happens on all resolutions, all frequencies (60Hz ad 120Hz) with HDR ON and OFF too.

[useryop2lhdtIz]

My Q80T auto-updated to firmware 1403.1 the other day. Not sure if that's what did it, but now I can get 4K 120Hz with HDR and Game Mode set to Auto without any issues. No flickering, no signal loss, and I can switch back and forth among all inputs to HDMI 4 without needing to toggle Input Signal Plus or unplugging the HDMI cable. Game Mode automatically turns on whenever I'm on HDMI 4, and I've even enabled G-Sync and played games for extended sessions without a problem.

Now that I've posted this, I'm sure I've jinxed it somehow, hah.

[userFO1OJGwZjh]

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@useryop2lhdtIz wrote:

My Q80T auto-updated to firmware 1403.1 the other day. Not sure if that's what did it, but now I can get 4K 120Hz with HDR and Game Mode set to Auto without any issues. No flickering, no signal loss, and I can switch back and forth among all inputs to HDMI 4 without needing to toggle Input Signal Plus or unplugging the HDMI cable. Game Mode automatically turns on whenever I'm on HDMI 4, and I've even enabled G-Sync and played games for extended sessions without a problem.

Now that I've posted this, I'm sure I've jinxed it somehow, hah.

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Same here. I used to experience white flickering when GSync was enabled but when I turned it on today everything was working well.

I have a q80t, firmware version 1403.1, RTX 3090 Gaming OC (Gigabyte), the newest NVidia driver (for Valhalla) and my cable is Savio CL-143, 3m long.

I have not tested other things you mentioned, as I always keep the game mode enabled and the only source I use is HDMI 4.