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

[RouDeR]

Happens to me with Movie / standard / Dynamic modes while using PC Input, I`m with the 8k Q800T

[Waldemard]

Same problem with 75 q95T, brightness fluctuates (Game Motion Plus on or off). All eco solutions turned off. System version 1115.

I’ve noticed another bug, when turning tv on with Game mode on and Game Motion Plus setting off backlight system behaves in a strange way. There is noticeable checkboard pattern, some tiles are brighter than others in checkboard pattern. Turning Game Motion Plus on and off or switching to another source solves the issue until tv is off again. Thinking about returning tv..

[jayh89]

I contacted a mod on here who said he has passed all the details on to HQ who should deal with it. Hopefully this happens fast!

[LCDeez]

I doubt they roll out fixes before the next firmware upgrade which has been every month so far. 

I agree with the other poster, game motion plus being off creates weird flash lighting issues and color clouding. They better fix this because everyone with a 4K or 8K (now at Q80, Q90, Q95, and Q800T) will notice this soon and lose their minds.

[Luke_H]

Glad you mentioned that, I to have experienced a slight grid shift in brightness at first I thought it may be at source, ie compression applied through sky and the *****ty data rates... looking closer it was defiantly what you discribe.

[LCDeez]

If you play FIFA at all, you'll notice a bright splotch appearing right in the middle of the screen while moving around in menus. I actually think FIFA is the perfect game to exhibit every issue so far with game motion turned off. 

[jayh89]

Fifa is good for seeing the entire screen dim effect. I've not saw any localised dimming like some of you mention e.g. middle of screen etc. 

[Luke_H]

il give this ago, I play fifa just haven't played it since having the set. Mainly COD warfare. 

[LCDeez]

Go open packs if you can, watch how the TV reacts in and out of the pack opening scenes.

[jayh89]

I had to turn motion plus off FIFA because it was causing a weird jittery effect... this is a nightmare. Samsung need to fix this asap.