BenQ EX3501R 3440×1440 21:9 35″ Curved VA monitor – line flicker (WHL #33F2)

Ahh, good old Christmas.

Been busy with other display-related things, but haven’t been using the BenQ at all. Now that everything is quiet and there are a couple days of vacation, I did fire up the system and played PoE for half an hour. And another half an hour to take some videos and photos. For whatever reason, there are now entire lines flickering during gameplay, and I claim these weren’t present the last time I used the thing. GPU driver update (still on 17.8.2 for my Radeon 260X)? Someone changed something in the PoE code (which caused an update of 600+ MB)? Me having seizures? Well, I have photo evidence, so I’d like to rule out the last one…

Getting ordinary images from such an event is a bit tricky, so I went to use the video or “high speed” video function on my Canon S100, which is 24, 120 or 240 fps in 1920×1080, 640×480 and 320×240 respectively. Conversion is easy on Linux, just use the convert command and choose an image format as output file. It’ll do it’s magic (imagemagick / ffmpeg), in case the file is a tad larger and your swap is too small, use something like

convert -define registry:temporary-path=./tmpfile -limit memory 2000mb MVI_3362.MOV MVI_3362.png

Back conversion to GIF is just as easy:

convert -delay 4 -dispose previous -loop 0 *.png animated.gif

(just do that in a subfolder with only the necessary PNGs in it – it’ll be so much easier than naming all files that shall be included in the CLI)

So, what does it look like? Starting from high res down to high temporal res – the images have been scaled down by ezgif.com, as I was too lazy to grab the source files again and run convert with the rescale option once again. One thing to note: The next four ones need to be opened in a separate tab due to the 1080p size, and they all may play at a different speed that is not necessarily 100% gameplay speed. This is 2017, and playing high-fps GIFs is still a dark art!

Still image:

Next one is a bit unusual, as it is not an entire line across the display, but rather a short strip on the very right:

Still image:

Still image:

And another one…

Still image:

Having only 24fps in that resolution, every glitch is only visible in exactly one frame. So I tried 120fps in 640 resolution; appearance is quite a bit different due to the camera running in a special mode:

It’s a pity there is no 100fps mode so that I can be in sync with the monitor, but from having the line appear and disappear within 3 images, I can conclude the upper limit of 25ms or 2-3 images on the display:

You can also see PoE is not running at max frame rate ;)

Going up to 240fps doesn’t really yield more information. Resolution is pretty…mediocre.

5 frames for the line to appear and disappear, equalling 21ms or 2 frames on the display.

Next one is another partial line, but that could be due to the dark image content on the edge of the map:

Same five camera frames -> 21 ms.

And another one in a similar location, only one second apart in real time.

This one is only 3 frames in total, which is 13 ms.

So for the most part, these line glitches are 2 100Hz monitor frames = 20ms long and appear randomly (in position and timing) on the screen. They are frequent enough to be captured easily by camera, which affects gameplay quite a bit. I initially thought this was due to frame drops at around 30fps, but that wasn’t the case for the 1080p footage in a less crowded area, which was significantly higher at around 50fps. It also has nothing to do with the low (“dynamic”) resolution switch introduced in the PoE 3.0 release that is usually active, but disabling or moving it to a different fps threshold doesn’t remove the flickering lines. If only I had some other current games to test this in different environments… ;)

I will try updating graphics drivers and see if that changes the effect. There were also some reports on the interwebs that the popular Samsung C34F791 34″ 3440 monitor does have flickering as well, but that is much reduced or even completely eliminated when run with a current Vega card instead of older, but still FreeSync compatible graphics cards like my 260X. I am actively thinking about a system upgrade, but it is nothing that will happen in the next weeks. And again – if that’s a driver issue, it might as well be fixed just by updating the driver when installing a different card. Guess that needs further investigation.

Bonus question: Which map was I running? :mrgreen: (easy one for PoE aficionados!)

[Please see the original post and the first follow-up as well.]


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