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

[DUSKTILLDAWN]

Well 1402.6 no good on q90t horizontal scrolling lines going up screen with GMP off and in freesync ,on Xbox in UK ,if yours is fine  get on with your life,for others this is a page for issues and many trolls on here,let's hope the you can be helpful, brightness dimming issue is fixed though.

[SidL]

Q95T

[SidL]

It is not about the dimming bug, but about 'local dimming'. You just have to do the test on a loading screen where the logo of a game is in the bottom corner of the screen and the rest of the image is dark, enable and disable the GMP you will see, or simply turn on the TV in game mode on the screen "no signal" turn off the ambient lights and activate and deactivate the GMP that will see the difference

[AzazelPL]

I have the same horizontal lines as You. With GMP off a lines that goes up are noticeable on every console (ps4, ps3 and ps classic). Its some game mode issue, I never seen anything like that on tv. I prefer GMP off because it has better color. I thing Samsung messed up something with the screen refresh to achieve a low imput lag. 

[jayh89]

Can someone get a video of these vertical lines? I can’t reproduce this on my tv. 

[QuantumP]

Same here, I do not see any lines.

[lmpcardoso]

If I turn off GMP on my Q80T the colors became inverted. I have opened a ticket on the support again, and they said the this bug will be fixable on the next update latter in the final trimester of the year. Some people said here that this bug it’s non fixable. Could be possible be fixable? If not, I will not be able to play with vrr on PlayStation 5... so I hope that Samsung is telling the truth. 

[Jihionfly]

Horizontal lines right?

[DUSKTILLDAWN]

Maybe certain models I'm on Q90T seen quite a few others seeing the same as me now,this is also showing on some people in us and UK,on ps and  Xbox it's faint but once you see you can't unsee it,don't have good camera here to catch it hopefully someone can show the the lines and they are horizontal going from bottom to top continuously,like an old 1990 TV which wasn't tuned in correct ,it's been like this for 3 firmwares I can't believe Samsung doesn't see it ,but if others don't I'm trying to work out why not,whack the backlight up to 50in game mode on ,not auto game mode disable GMP and look at settings screen grey background on Xbox just watch screen ,this is also showing on freesync as that disable s GMP automatically as you can't have both on .