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

[Toejo78]

I think its always hard to tell on normal TV.  Its great on Netflix etc, did you think normal viewing wasn't up to scratch?

[Mordechai]

For me dimming is still there in PC Mode + Game Mode...

[ad1994]

Standard and High do look more or less the same on 1304 imo

[DUSKTILLDAWN]

This update no good with game motion plus on and notch to 1 same as before ,with game motion off and HDR on ,scrolling lines on Xbox settings grey background on q90t ,also freesync HDR still darker than movie mode, unplayable for me with freesync anyway,game dimming issue not there but other issues hgig makes pic slightly darker,look at edges of screen tested with HDR warzone ,and freesync HDR warzone,like i say faint scrolling lines on grey settings background with freesync and game motion off .

Xbox oh well..

[daparky]

How is local dimming? Is blooming an issue?

[Iskandarkebab]

For me It looks awsome right now on PS4 pro. Im playing Ghost of tsushima and dark areas now appear with more detail and less blueish than before. Hgig does make some areas darker, but increases contrast so for me It looks better with It on. No dimming issue anymore.

[TomasTSH]

I haven`t updated yet, and I`m on PS4 Pro, and ye I can see the faint scrolling lines on grey background too with GMP off. Will check how it is after the update.

[DUSKTILLDAWN]

Yes please do I've updated and still see faint scrolling lines with GMP off on Xbox grey settings menu for example,with GMP on there gone ,and there gone with freesync but that's way too dark..

[Vagval13]

Tested the new firmware for a bit. People need to realize something. 
1) As long as Samsung prioritizes that under 10ms input lag time, local dimming will never function as intended in game mode. Very simple test. Put gears 5 loading screen that really tests tv. On game mode no matter how much the algorithm tries you have some blooming. Also transitions in dark areas trip it. Try the same loading screen on movie mode with dimming on high and it is pitch black. So yes some blooming is there. 
2) I see people talking about some banding and/or ghosting. Again from the time picture clarity and noise reduction is disabled in game mode people should expect some of this. For me it is faint. Almost unnoticeable because they did indeed improve it. Also people who have hdr in 4k must buy an ultra high speed cable with 40gb/s bamdwith. It mitigates some of these issues. Many people have 1.4 high speed cables with 18gb/s bandwith and it just doesn't have enough bandwith for 4k with hdr. It helps trust me. 
3) I see some people saying hgig dimd the picture. That is wrong. Hgig is actually all the money on this update. What you think is 'dimming the picture' is actually producing more accurate hdr results without clipping or light bleeding from sources and makes for an overall much better hdr image. Just give some time for your eyes to adjust to the change. It is worth it and must always be on in hdr game mode. Trust me on that. 
Q80t 49 inch owner here btw. 

[DUSKTILLDAWN]

Is your console in port 4mine is just asking people in general