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


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

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Yeh I've tried that. It's something to do with local dimming with HDR sources. Wish Samsung could help! 

Ah, I see

To be honest im pretty sure ive disabled all eco setting anyway. Would love some help from an administrator with this, clearly seems to be a known issue.

I've tried absolutely everything. The only thing I haven't tried is going I to the service menu (which Samsung don't like you doing and it might even void a warranty). I want Samsung to issue a simple software fix. It's absolutely fixable.

Yeah im reluctant to do that. Ive heard examples of people going in and turning off local dimming etc..


I just spoke to Samsung on chat and they said they would report this to the engineers... we shall see.

Good work buddy. I had done the same, surely if enough people are flagging this then it becomes and issue. Which it obvioulsy is?!


Same bug on q95t, im about to give the TV back.


Yup, same issue on the US Q90T. Game mode dimming occurs but only when game motion is completely turned off. Also, a little ghosting happens as well in some games (not inverse but more like blown out highlights and weird light pulse stuff). It will always happen like the OP mentioned and dims probably close to 20 or 30 of the total brightness. The real problem I have with this is that I want to take advantage of the super low input lag but the only way to play games right now is to have both game mode and game motion on together. Input lag with these two hovers around 22ms. 


Samsung swapping or are you jumping ship?

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