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Issues with backlight strobing, scrolling bars (title edited)

Dammett
By Dammett
in Displays
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I bought a new Samsung 31,5" C32H711 1440p 60Hz monitor about two weeks ago. The first unit had a dead pixel, so I took it back to the store and got a new one of the same model. Now after about a week, I began noticing dark, downwards scrolling horizontal "bars", about 10cm (approx. 4 inches) "thick" and width of the entire monitor. (Not sure if they've been there the whole time, haven't really had that much time to play with the monitor). The scrolling bars can only be seen against a rather dark background, for example YouTube with the new dark theme, or for example Spotify on full screen, when the brightness of the display is below 50 from 100, even at 0, which is still bright. The bars are obviously always darker than the background. It takes about two seconds for each line to reach from top to bottom and the screen can fit 1-2 scrolling bars at a time, which gives some idea of the scrolling speed.

 

The monitor is connected to my 4 year old GPU, EVGA's GTX 760 with a DisplayPort cable, but it doesn't make a difference if it is connected with an HDMI cable instead.

 

Anyway, the monitor has FreeSync, which my GPU doesn't, so why is it that if I go into the monitor settings and set FreeSync to "Standard Engine" or "Ultimate Engine" instead of "Off", the dark scrolling bars disappear? And is the monitor faulty as I can't have FreeSync set to "Off"? Or is it my GPU, even though there was no issue with the old Full HD monitor? Or is it just plane normal? Even Samsung support doesn't know the answer to this.

 

The monitor is going back for the second time anyway, as this one also has a faulty pixel of some sort, which can be seen against a dark background, but would just like to know if this scrolling bar thing is an issue that should be accepted with the current GPU or whether the monitor is faulty in that sense. Thanks for the help in advance, not really an expert in this area.

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I'm not really sure but, even if you have on or off it shouldn't change anything or in your case make the black bars appear and disappear. If you switched cables and it still happened then we know it's not the cables. My guess is that your settings might be changed somewhere (where you haven't looked) or your gpu might have something wrong. Try switching gpu's, that will clear settings, drivers, and the gpu itself and hopefully work. If not then it's just the monitor.

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21 minutes ago, Dammett said:

I bought a new Samsung 31,5" C32H711 1440p 60Hz monitor about two weeks ago. The first unit had a dead pixel, so I took it back to the store and got a new one of the same model. Now after about a week, I began noticing dark, downwards scrolling horizontal "bars", about 10cm (approx. 4 inches) "thick" and width of the entire monitor. (Not sure if they've been there the whole time, haven't really had that much time to play with the monitor). The scrolling bars can only be seen against a rather dark background, for example YouTube with the new dark theme, or for example Spotify on full screen, when the brightness of the display is below 50 from 100, even at 0, which is still bright. The bars are obviously always darker than the background. It takes about two seconds for each line to reach from top to bottom and the screen can fit 1-2 scrolling bars at a time, which gives some idea of the scrolling speed.

 

The monitor is connected to my 4 year old GPU, EVGA's GTX 760 with a DisplayPort cable, but it doesn't make a difference if it is connected with an HDMI cable instead.

 

Anyway, the monitor has FreeSync, which my GPU doesn't, so why is it that if I go into the monitor settings and set FreeSync to "Standard Engine" or "Ultimate Engine" instead of "Off", the dark scrolling bars disappear? And is the monitor faulty as I can't have FreeSync set to "Off"? Or is it my GPU, even though there was no issue with the old Full HD monitor? Or is it just plane normal? Even Samsung support doesn't know the answer to this.

 

The monitor is going back for the second time anyway, as this one also has a faulty pixel of some sort, which can be seen against a dark background, but would just like to know if this scrolling bar thing is an issue that should be accepted with the current GPU or whether the monitor is faulty in that sense. Thanks for the help in advance, not really an expert in this area.

Sounds like backlight strobing but with a low frequency (i.e. bad implementation). Lowering brightness will decrease then length of the strobe, which will make it more visible at low frequencies. Strobing will also be disabled automatically when FreeSync is enabled since they are incompatible.

 

There's probably a dedicated setting for turning it off besides using the FreeSync setting, usually it's called something related to motion blur reduction.

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On monitors like mine there are many settings and when certain settings are enabled others are disabled. So when i turn on freesync on my monitor some settings are disabled and cant be turned on. My guess is when you turn on freesync some settings are disabled and that gets rid of the black bar.

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49 minutes ago, Glenwing said:

Sounds like backlight strobing but with a low frequency (i.e. bad implementation). Lowering brightness will decrease then length of the strobe, which will make it more visible at low frequencies. Strobing will also be disabled automatically when FreeSync is enabled since they are incompatible.

 

There's probably a dedicated setting for turning it off besides using the FreeSync setting, usually it's called something related to motion blur reduction.

This is interesting. It appears to be true that the lower the brightness, the thicker the bars, ranging from about 1cm thick with brightness at 0 to 10cm thick with brightness at 50.

 

I honestly can't find any setting in the monitor menu that helps except FreeSync and modes, i.e. Gaming Mode, which set the brightness to 100. However, even in gaming mode, when the brightness level is lowered to under 50, the bars are back. There is a submenu under "System" called "Response Time", altough it doesn't have any effect by itself. Does perhaps the information menu give any clues? It says:

DisplayPort

2560x1440

88.8kHz  60Hz

 

When FreeSync is enabled, the 88.8kHz  60Hz text is replaced with "FreeSync"

 

I guess I'll also try the display reset option, even though I haven't really changed anything except brightness and contrast. GPU drivers were cleared and re-installed yesterday, I could yet do a clean install of those and reset the GPU settings, although I don't recall changing them either.

 

The entire settings menu of the display:

  • Spoiler
    • Picture
      • Samsung Magic Bright (no effect)
      • Brightness (below 50 brings back the issue)
      • Contrast (no effect)
      • Sharpness (no effect)
      • Color (no effect)
      • Samsung Magic Upscale (no effect, "enhance picture detail and vividness")
        • Off
        • Mode1
        • Mode2
      • HDMI Black Level (can't use)
      • Eye Saver Mode (no effect)
      • Game Mode (no effect other than spike up the brightness)
        • Off
        • On
        • Alwayay On
      • Response Time (no effect, "Accelerate the panel reresponse rate to make video appear more vivid and natural")
        • Standard
        • Faster
        • Fastest
      • Picture Size (no effect)
        • Auto
        • Wide
      • Screen Adjustment (can't use)
    • OnScreen Display (configures on-screen menu's appearance only, no effect)
    • System
      • FreeSync
        • Off
        • Standard Engine
        • Ultimate Engine
      • Eco Saving Plus
        • Off
        • Auto
        • Low
        • High
      • Off Timer (no effect)
      • PC/AV Mode (no effect)
        • DisplayPort
          • PC
          • AV
        • HDMI
          • PC
          • AV
      • DisplayPort Ver. (no effect)
        • 1.1
        • 1.2
      • Source Detection (no effect)
        • Auto
        • Manual
      • Key Repeat Time (no effect)
      • Power LED On (no effect)
      • Reset All
    • Informaton (no effect)
      • DisplayPort
      • 2560x1440
      • 88.8kHz  60Hz

     

 

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16 minutes ago, Dammett said:

This is interesting. It appears to be true that the lower the brightness, the thicker the bars, ranging from about 1cm thick with brightness at 0 to 10cm thick with brightness at 50.

 

I honestly can't find any setting in the monitor menu that helps except FreeSync and modes, i.e. Gaming Mode, which set the brightness to 100. However, even in gaming mode, when the brightness level is lowered to under 50, the bars are back. There is a submenu under "System" called "Response Time", altough it doesn't have any effect by itself. Does perhaps the information menu give any clues? It says:

DisplayPort

2560x1440

88.8kHz  60Hz

 

When FreeSync is enabled, the 88.8kHz  60Hz text is replaced with "FreeSync"

 

I guess I'll also try the display reset option, even though I haven't really changed anything except brightness and contrast. GPU drivers were cleared and re-installed yesterday, I could yet do a clean install of those and reset the GPU settings, although I don't recall changing them either.

 

The entire settings menu of the display:

  •   Reveal hidden contents

 

Yeah, doesn't look like there's any option that would control it, if what I said is correct.

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6 minutes ago, Glenwing said:

Yeah, doesn't look like there's any option that would control it, if what I said is correct.

Would you then say the monitor is faulty or no? As I have no idea...

 

1 hour ago, Glenwing said:

Sounds like backlight strobing but with a low frequency (i.e. bad implementation). Lowering brightness will decrease then length of the strobe, which will make it more visible at low frequencies. Strobing will also be disabled automatically when FreeSync is enabled since they are incompatible.

...and as this sounds quite legit seeing the issue.

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Well, I returned the Samsung C32H711 monitor and got a new one of the same model, which would make it the third unit. This one also has the same issue, but the scrolling bars aren't quite as thick and are slightly less visible, though still obvious when looking at a dark gray background, for example. This unit also has a dead pixel on the side and a darker rectangular spot (width 1cm x height 3,5cm) in the middle of the screen, so back it goes for the third time.


It would still be interesting to fully understand why these vertically scrolling bars appear when set to low brightness and how such a thing can apparently be a feature of this quantum dot monitor. Is it perhaps a feature on all modern displays with low brightness? All I've learned is that it most likely is backlight strobing of some sort, as Glenwing said earlier, but it doesn't really appear as flickering, as in most cases found online under the subject.


Also, would the same issue be perhaps expected to be found on the Samsung C32HG70, which is a similar display, but 144Hz instead of 60Hz? Both are basically quantum dot displays.

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