2020 QLED T models (Q80T, Q90T, Q800T, Q900T) HDR game mode brightness / local dimming bug

[Rauttis]

I bought a Q80T a couple of days ago and have noticed a really annoying issue when using the tv with the combination of HDR and game mode.

I'm fairly certain this is a software bug in the TV since I can reproduce this issue with 100% accuracy, and it happens on the dot at the same moment every time. It's basically on a timer.

Basically when the game is displaying a HDR signal and game mode is enabled, exactly after 6 minutes the brightness of the TV suddenly drops by around 20 (50 -> 30). The value of brightness setting doesn't actually change however. Messing with the brightness setting does not restore the brightness to it's original state, but changing the local dimming setting from standard to low and then back to standard does. Switching game mode off and then back on also fixes the issue, but then it happens again EXACTLY after 6 minutes (I've timed this with a stopwatch).

Has anyone else experienced this issue? Or can someone maybe test this on their TV to see if you can reproduce it?

Exact repro steps on how I can reproduce this 100% of the time on the PS4 Pro:

1. Set brightness to max (50)
2. Set local dimming to standard (bug happens on high as well)
3. Enable game mode
4. Turn off game motion plus
5. Turn off intelligent mode and all the brightness related settings in eco settings, as these can influence the brightness level of the tv.
6. Launch a game that runs in HDR
7. Start your stopwatch
8. Do whatever you want in the game or you can also go back to PS4 menus, find a bright scene where you can notice a brightness drop easily
9. When the stopwatch hits 6 minutes, you should see the TVs brightness suddenly drop by a large amount. By eye the brightness drop seems about equal to dropping the brightness from 50 -> 30 by hand.
10. Go to picture settings and set local dimming to low (brightness does not change)
11. Set local dimming back to standard (brightness suddenly jumps to the original level. Brightness can be restored by switching input away and back as well, or by disabling and re-enabling game mode)
12. And again after EXACTLY 6 minutes the bug again repeats and the brightness drops down again

Some other notes: The PS4 has a screensaver that basically dims the screen if it is idle for a while. This is not the cause of this, this happens even when the console is in active use and the brightness can be restored temporarily by changing the local dimming setting like described above. I have not managed to reproduce this issue with game mode off, so it seems to be related to game mode.

Software version: 1304

[jayh89]

What flashing brightness bug are you seeing? Can you give more detail?

[Duner]

will do a movie on put it on tube and post here

[MvdLaar]

Even though the problem seems to be different, does "resetting" the local dimming manually work for people? I recorded a video for another thread on an issue that I've been having where local dimming works perfectly, but only after manually setting it to the same setting (standard) again:

[PawelMerlin]

Could you post the video in higher quality? 360p does not tell much.

[MvdLaar]

Gotcha, I ripped it from a Messenger conversation with Samsung. Here's the original 1080p (although the glow itself is very visible even in the 360p version):

[aracunliffe]

Just came across this thread after having the same issue as OP but with my brand new 65" Q90T.  Oddly enough, it's happening to me in Movie mode while streaming content on Amazon Prime.  6 minutes, like clockwork, then it dims dramatically.  I have to go into the Local Dimming option and flip it to Low, then back to Normal, to fix it.

Has Samsung addressed this issue in any way?  Has anyone figured out a fix?  I'm absolutely dreading the possibility that I need to return this gigantic thing.

[aracunliffe]

Hey Quantum, I'm in the exact same boat here.  Just got a 65" q90T two days ago.  Dims at the 6 min mark on Amazon Prime, but also when I'm watching movies on a USB drive, and I'd assume all the other streaming apps as well.

I also read about how this used to be an issue with Game Mode, but they fixed it?  If that's true, and if this auto-dimming bug was introduced by a recent firmware update, then I'm optimistic they can fix it with another firmware update.. but it's hard to say whether this is a software issue or a hardware issue since I just got the TV.  

Any updates on your end?

[Andrewt81]

I own a Q95T and an RTX 3090.. I'm interest in update for VRR but can't find 1403 update on support page (latest is 1304). How to update? I'm from italy

[AZGreg]

So apparently the 6 minute dimming bug is back in non-game modes now? WTF...

I use standard mode and avoid game mode on my Series X due to the vertical scan lines, but now I don't know what's worse with the dimming.

Easy for anyone to replicate by going into the HDR Calibration app and looking at the brightness checkerboard pattern. After about 6 minutes, boom, dimmed! The crazy thing though is that you don't have to mess with local dimming settings to revert it, just hit the guide button!

Samsung needs to get this sorted out...

[teosc]

I am going to buy a 55 q80t to use as a pc monitor.

1. Does the bug currently occur even outside game mode?

2. With the latest updates, is game mode required to activate gsync with nvidia 3000?