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

[Suriya]

May be for you this update didn't broke anything on q85t. but in q95t it's different

[Suriya]

Like somebody said movie mode has low input lag. after adjusting some settings

Games looks amazing never seen anything like this before any OLED can't do this 0 blooming, OLED like blacks with outstanding brigthness Fully effective local dimming.

Movie Mode:

Brigthness 50

Contrast 50

Sharpness 10

Clarity OFF

Local dimming High

Contrast enhancer High

Warm2

Gamma 1886 with +2

Color space Native

[LCDeez]

Who said this? I haven’t seen hard evidence that movie mode has low input lag outside of game mode. You’d have to back that up with some legit numbers from a real input lag testing tool. 

[RouDeR]

1440p or 4k/120hz Movie mode have less input lag than 4k@60 game mode
https://www.youtube.com/watch?v=67ASNa4X5GE&t=2s

[SidL]

Has anyone tried to restore the TV through the service menu to see if update 1304 is uninstalled?

[Jihionfly]

How to enter and restore from service menu for q90t?

[Suriya]

Pls try yourself and see you'll see no differences between movie preset or game-mode. Tried 4 games on my ps4 pro

[Suriya]

Pls do the same comparison video with

"4k 60hz/ 1440p 60hz" between game-mode and movie mode

[jayh89]

You’re suggesting it’s a heating issue, which means it’s hardware related and a much bigger issue. I also have intelligent mode OFF, otherwise the same settings. I’d be very surprised if a simple fan solved internal heating issues... this problem just gets more strange. 

[Alekkk]

If that fan is really doing anything then you should be able to switch it off and then observe the dimming again, right? Correlation does not imply causality. If you want to really test this, you need to keep all the other variables as constant as possible so you are only manipulating what it is you want to test. This is almost certainly a software issue, which it seems Samsung is going to do absolutely nothing about. Otherwise why would Movie mode not have the same problems with dimming? Movie mode does MORE image processing, which is why it has higher input lag. It should tax the hardware MORE, not less.