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.

[user89h75LbZwn]

wow i am glad i found this forum,  i have the qn75q80t and have been going crazy cause i purchased it for the 120hz.  I only purchase samsung tv but when the flickering started i was going to return it as faulty, but now i see its an issue that every is getting. i really hope they address this issue soon,  i am using it with my rtx 3090 the flickering is disappointing 

[user89h75LbZwn · Accepted solution]

i have an update on my end hopes it help anyone else in the same positon. I purchased the belkin hdmi 2.1 certified cable from amazon this is the model #AV10175bt2M-BLK, and the flickering went away as soon and i hooked it up to my 3090 to the tv. 

[userH8wTIoixjN]

I've spent time trying to get my q80t to play with all the bells and whistles to my pc with a rtx 3090.  It took a cable switch to get it there.  Needed a long run, 16feet to the pc so the standard ones for 30-40$ on amazon just weren't cutting it, zeskit got me close.  Could get it all turned on, the 4K/120, vrr and hdr but once I got into games the flickering would hit.   

tried a super expensive cable, audioquest, and sure enuf it worked.  I don't personally believe pictures get better with more expensive cables. I get the, it either works or it doesn't but I think I needed a better built cable due to the length of cable I needed so switching to a cable using silver instead of all copper as the conductor got me over the top.   

I guess just throwing this out there if anyone else ever comes by looking for similar help.  I know I scoured the Internet for days for help.   For me, to do a long run of 16 feet to the pc from the tv and get 4k/120, vrr and hdr to all work on the hdmi 2.1 port on the q80t, I believe I had to get a better built cable with some silver conductor material in it.  

the zeskit cable was fine on the 2.0 hdmi ports but the issue was, going to 4k/120 on those ports disables hdr.   The solution I believe is to go down to 60hz but the only options under pc resolutions at 4k I was getting was 120 or 100hz, no 60.  Going to the tv resolutions on the nvidia control panel as opposed to the pc resolutions and selecting 4k would have everything turned on, 4k/60, vrr and hdr but the vrr fails the nvidia pendulum test.  Tv says the feature is on but the screen still tears.  It has to be the pc resolutions.  Had the pc resolution had 4k/60, I would have stuck with that instead of upgrading to the stupidly expensive audioquest cables.  

I guess bottom line, if I paid what I paid for a rtx 3090, the cable is par for the course lol.  Anyway hope this helps someone down the road.  

I do have the ps5 snd Xbox series X, the zeskit cables I was using worked fine to maximize everything those consoles offer respectively.  

[userku5bgReNoJ]

hi all,

So I'm not the only one.

PC connected to my QE55Q80T with ultra high speed HDMI 2.1 cable, perfectly working (no artifacts, perfect signal...), HDR 4K @120Hz with VRR and game mode enabled, but if:

- I switch on my PC first,

- switch off my TV, then on again a couple of minutes later

- get my GPU crash and reboot (PC & windows still running)

then I get the no signal message and I'm forced to play with "signal plus off / on" or it also works with disabling & enabling game mode.

But hey, for a new TV supposed to handle 4K 120Hz I was expecting less troubles!

Any udpate from Samsung or any way found to fix this?

[userZdkCLxi8vE]

I have a stable signal, but i get massive purple ghosting and VRR-flickering, really strong at 50FPS somehow, like in Cyberpunk. I use the same HDMI cable with works perfectly with my C9. 

Anyone else getting massive purple ghosting and flickering around brigth objects like street lamps at night? Its way more obvios between dark and bright objects.

[CJx]

Are you on the latest firmware?
The purple ghosting was a big issue with these TV's on release but was addressed in a previous firmware patch.

[userZdkCLxi8vE]

Yes i'm on the latest FW. Well, many people still have issues with it, AVSforums etc.

So i guess there is still something wrong. I did some factory resets too.

Here is what it looks like:

https://www.youtube.com/watch?v=1BJGOLD5Ehw

[user5gYQIW4Zrv]

its 3rd of april and i have new Q90T and the same problem like you guys. 4th HDMI Port and backlight is flickering. Any new updates of you guys?

[99xexp]

Hey, OP here.

The flickering issue was resolved for me after the 1402 firmware update a few months ago. I'm currently using one of the Zeskit cable a few users mentioned in this thread, alongside with no gamemode enabled and 4K120Hz w/ 4:4:4 subsample.

Try checking your TV firmware version against the latest one posted on Samsung's website for Q90T. I know that a few of the updates in the past weren't available via automatic updates on the TV and had to be done using a USB device.

[user5gYQIW4Zrv]

hi, i bought the q90t as an upgrade for my Q9FN. Key feature is 4k@120hz with VRR / G-sync because i use the tv as an monitor. 

i bought a ultra high speed 2.1 hdmi cable and first my 4th port worked but i had backlight flicker. now im not able to use it any more because when i go do game mode, my screen on TV freezes instantly. nvidia drivers are the newest on my 3090. firmware also (1497). i try to reinstall firmware over usb. seems for me that the game mode is kind of broken. i have also artefacts in games when there is a scene with grey colour. if i disable game mode, picture is fine. when i cant fix it, it will be my last samsung tv 😞

regards