Good News - A 1440p 240hz without eye strain found, but there's bad news

[r0ach]

Tried several monitors lately such as:

- Koorui 27E3QK 1440p 240hz
- Asus XG27AQMR 1440p 300hz
- Acer XV272U W2 1440p 240hz

The Acer was the only one I really found bearable eye strain-wise. Contrast and black levels on the Acer were pretty close to the $600 Asus. The Koorui image quality and contrast were a lot worse than both (probably some type of B-grade panel and not representative of a real AU panel).

Now here's the downsides. Even with overdrive turned off, the Asus seemed to be a subjectively faster and smoother motion experience at both 300hz and 240hz. This is something I can live with but the bigger problem is that the Acer W2 has noticeably less responsive/more heavy cursor movement. You can try turning DDC/CI on/off and all the other options and none of it fixes it. It's kind of how the Asus feels with DSC turned on, but at least there you have the option of running 300hz with YCBCR 422 and DSC off for less heavy cursor movement (DSC on for the Asus feels even worse btw).

And here's the most annoying part. The Koorui absolutely blows the doors off both of them in terms of cursor movement. It's a lot easier to aim with it than either of the other two. On most monitors I typically notice the cable that comes with it not working well for optimal aim and you'll have to do something like throw away their generic 30AWG cable and use a better 26AWG or something instead. No such problem on the Koorui. You can either use their ultra-budget Displayport cable straight out of the box or any in your house and it feels excellent.

I've been using this roguelite FPS game called Deadlink to test aim lately. It's basically the same thing as an aim trainer as it just dumps a bucket of enemies at you then you kill them and proceed to the next area to do the same thing. On the Koorui I can pop off literally 100 headshots in a row with no misses. On the other two monitors it's not even close and you're basically contemplating aiming for the body instead. Let this be a lesson that monitor firmwares are not even remotely similar for cursor movement.

The Koorui monitor firmware doesn't even make sense as it's set to "HDR: Auto" by default with Aspect ratio being set to a similar setting instead of 16:9 or "full" like most panels you see nowadays. If you change either of these settings you'll immediately notice mouse movement turns to total garbage and feels abnormal, but leaving everything on default it's just perfect for cursor movement in terms of linearity and responsiveness. If you want bad image quality, feeling like your eyes are swelling in your head after one hour of use, but the ability to become the best FPS player on Earth, buy the Koorui.

As for the Acer W2, I'd like to find out what panel and backlight configuration it uses for future reference for eye strain. It looked kinda similar to the Innolux in image but when you look at the Acer from below or the side you can see a small gap between the outer and inner screen (kinda like the cheap ipads) that you see on a lot of panels with this 'frameless' design nowadays. The Asus 300hz with Innolux panel doesn't have that gap and looks like an actual laminated screen, so I'm probably leaning towards BOE, but it's possible it's just a different Innolux panel. It didn't look like any AU panel I've ever seen, though.

[Chief Blur Buster]

Great observational information for those who are testing LCDs, as long as caveated as "YMMV".

Be noted, I must caveat that people eyestrain differently -- I've witnessed people get vice-versa.
Person A (e.g. >50% of eyestrainer population): "I got eyestrain from Model ABC but not Model XYZ"
Person B (e.g. <10% of eyestrainer population): "I got eyestrain from Model XYZ but not Model ABC"
Or neither; or both.

However, it is quite useful information for others to try out for themselves.

It's often very hard to determine why this happens, but different people were bothered by:
- Liquid crystal screendoor structure; and/or
- Antiglare film type; and/or
- Brightness; and/or
- Ghosting behaviors; and/or
- More blur; and/or
- Less blur; and/or
- Blue light and/or shape of color spectra; and/or
- PWM dimming; and/or
- Pixel flicker/dither behaviors (FRC/visible inversion/etc) behaviors; and/or
- Etc.

My past experience is that even if it's almost certainly a backlight related thing, it's often (double digit percentage of the time) traced to something else.

Even zero transients with weird color spectra shapes (excess blue, despite a Low Blue Light mode), can also sometimes explain thing from an ergonomic issue.

Other times it was a red herring (e.g. slower pixel response was more comfortable on the eyes -- the "Reduce Motion" assistive-setting folks often find 24Hz refresh rate to be more ergonomic to them).

There's also the upside too (reduced eyestrain from less ghosting), which is why sometimes even ugly TV interpolation ends up becoming a defacto "assistive feature" to them. Either way, the double edged sword goes both ways. We've had a few high-Hz fans sadly have to discontinue high-Hz community due to a newly developed intolerance, so this is a real thing.

Some ergonomic issues are pretty common (>10% population) and others are semi-niche issues (<10% population), and others are outlier issues (<1% population). Trying to narrow down why Model ABC doesn't eyestrain like Model XYZ (or vice versa) is tough. Make sure you have a colorimeter to configure them to the same brightness. But if you kept all of them (+rep if you did), go ahead an analyze all of them into a spreadsheet of each possible ergonomic issue, and measure each attribute scientifically.

Such niche scientific-league analysis work is something fairly low-ROI once you're beyond common stuff sadly. Which means not enough ability to earn money off these niche science items for monitor reviewers to cover. It's almost just too big a rabbit hole sadly, so industry narrows down to just a few widely known ergonomic issues, while the truth is over 100+ ergonomic issues exists, once you're going to those "what affects 1% of population" lineitems. But as an aggregate, that's still a lot of population once combined together. That is the kinda stuff that slips into the cracks, untested.

If you initially focus only on backlight-related culprits, I suggest comparing:
- Track down spectrographs to measure the shape of the color spectrum of each panel
- Track down oscilloscope graphs to measure whether it has PWM at its ideal brightnesses
- Make sure you calibrate its brightness to equal (~120 nits is recommended Office brightness, with high brightness mode reserved for gaming).

Failing that, you drill down to other troubleshoots; for temporal flickers that are not backlight related, you can branch out to:
- Determine if it has inversion artifacts (chessboard or lines textures in moving blocks of solid colors)
- Determine how your vision reacts to different frame rates with the monitor's current pixel response abilities, as stutters is a component of the stutter-to-blur continuum (see www.testufo.com/eyetracking#speed=-1 while watching 2nd UFO for 30 seconds); slower GtG shifts the stutter framerate threshold lower, as slow pixel response hides stutters(a form of eye-straining edge flicker) better. Do not dismiss this cause; it affects more people than the industry claims -- that's one cause of OLED eyestrain because LCD stops stuttering at 45-50fps but OLED requires 70-85fps to stop stuttering, since zeroed-out GtG turns your perfect-framepacing (non-erratic) stutter threshold identical to flicker fusion threshold. For proper high framerate OLED ergonomic comfort, always use high frame rates, if you get eyestrain with "fast GtG + stutter" (surprisingly common cause of eyestrain that people never acknowledge, until scientifically tested into their faces; and wow, oh boy, wow, common cause).
- Determine whether it has FRC.
(Occasionally, you can sometimes eyeball it by intentionally switching temporarily to 60Hz or even CRU 48Hz and viewing extremely dark patches (RGB 0,0,0 vs 1,1,1 vs 2,2,2 vs 3,3,3 vs 4,4,4 vs etc). The low Hz allows the temporal dithering to become human visible, so you can watch the temporal dithering noise in action and compare screens. Make sure you use brightness 100% temporarily during this FRC eyeballing test. Not everyone can see this, but when lacking scientific measuring equipment, one must "make do")

Failing that, it spawns off to a lot of other troubleshoots;
- Antiglare textures/reflections
- Etc.

That said, keep an open mind to other unexpected culprits. >90% of people I met, that I helped troubleshoot completely all the way to completion, in a scientific manner, was from unexpected causes other than the common ones they thought were culprits. Sadly, the Internet is full of assumptions that eyestrain is cause X while it's actually cause Y, etc. It's also even a mix of multiple.

While displays are far better than they used to do be at doing this -- they are imperfect simulated images that don't have the same characteristics as the photons hitting your eyes from real world objects. Temporal issue, light-illumination color spectra, finite resolution, finite refresh rate, etc.

TL;DR: The gigantic spectrum of ergonomic issues is because all displays ever invented by humankind are artifical windows trying to simulate real life. Something is always off, and could affects your ergonomic comfort.

[r0ach]

We've had a few high-Hz fans sadly have to discontinue high-Hz community due to a newly developed intolerance, so this is a real thing.

I guess it's not out of the realm of possibility but I wouldn't be surprised if they misdiagnosed themselves because much of the worst of the eyestrain and PWM-like effect panels started appearing around the same time monitor hz took off (which also of course coincides with the extreme wide gamut KSF & quantum dots as well).

I've noticed actual motion fluidity/lack of microstutter varies a lot per monitor of the same hz as well. Like the Asus XG27AQMR frame delivery is very smooth, plus the Koorui 27E3QK was as well, but the Acer W2 seemed to not be quite as good in that department. It's not enough to cause any form of 'sea sickness' for me but the subjective user smoothness experience definitely varies. Whether it's something about timings or the controller boards have been skimped on and are choking in some way I'll leave that to someone else to figure out.

Youtube comments like this are usually borderline useless due to too many people with zero hardware experience, but it seems this guy noticed some issues with the frame delivery on that monitor as well:


*now you know why it was discounted to $229 on Amazon ranking it the cheapest 1440p 240hz monitor on the planet...

[Chief Blur Buster]

I guess it's not out of the realm of possibility but I wouldn't be surprised if they misdiagnosed themselves

Certainly.

Misdiagnoses happen. Especially when it's troubleshooted in a forum. And with most people other than me.

Yes. Even, I myself, can misdiagnose. But I do it much more rarely than the average person, especially if given enough equipment to test all possibilities out (e.g. including 3 types of LCD *and* OLED, plus some measuring equipment like my oscilloscope and photodiode, 1000fps high speed camera etc). Occasionally some rich guy is so desparate, they need a professional that's more surgical than a gaming-display-inexperienced eye doctor, so that they can bring more information to their eye doctor.

because much of the worst of the eyestrain and PWM-like effect panels started appearing around the same time monitor hz took off (which also of course coincides with the extreme wide gamut KSF & quantum dots as well).

Do you know that I have been PAID to spend hours diagnosing one on one, some peoples' eyestrains -- I can assure you that you're bringing up a false narrative / redherring factor (common at other forums) in this conversation. While you're correct a percentage is misdiagnoses, I can assure you that motion sensitivity maladies exist. So I'm nipping this in the bud here with factcheck before it snowballs to myth status;

That's why people like Apple/Android has a "Reduce Motion" setting and "Limit Animations To 60fps" setting in their settings.
Example: Reduce Motion on Apple Devices.

There's also the opposite end of the spectrum, a motion blindness called Akinetopsia [nih.gov, Wikipedia]. It's a rarer condition though.

The problem is that nobody sees exactly the same way. 12% of humans are color blind to varying degrees but there's also the undiagnosed slightly decreased color sensitivities (and motion sensitivites, and tearing sensitivities, and stutter sensitivities, and lag sensitivies, etc). There's degrees of different motion sensitivity.

Different humans are picky in different ways, and I do not humansplain or visionsplain people like most forum members. I keep an open mind to all of them; and I do unceremoniously ban 2+2=5 ardent flatearther skeptics from these discussion forums.

We are all about sciences/physics here, and we acknowledge & respect the people who prefer to see more display motion blur instead of less. High Hz is usually a gigantic ergonomic benefit, but there's the opposite edge to a double edged sword.

No two humans see alike.

[Chief Blur Buster]

*now you know why it was discounted to $229 on Amazon ranking it the cheapest 1440p 240hz monitor on the planet...

Monitor-side stutter can be caused by many problems:
1. Undiagnosed frameskipping issues (see 240Hz FrameSkipping Thread)
2. Pixel response being unusually fast (see Why Does OLED Stutter More Than LCD)
3. VRR bugs in firmware, if stutters only happens during VRR. You need to keep gametime:Present()time:photontime time-relative as pserfect as possible during VRR, so the temporal chain can break due to monitor-side VRR firmware bugs too.
4. Other weird bugs in firmware. I've seen them all. #DumbMistakesOfFirmwareDevelopers
5. Other

I'd put my gamble-money on item #1, you can see how old the Frameskipping Stutter thread is (2017). Even helped a few monitor manufacturers fix some of 'em, thanks to my very own www.testufo.com/frameskipping debugging test. Sometimes it only happens at certain obscure monitor settings, or bug only happens if VRR is turned off, other times it's fixable by a modified mode, and other times it needs a firmware upgrade. So I've seen units that stutter only when VRR=ON, and units that stutter only when VRR=OFF, for completely different kinds of stutter-bugs in firmware.

But it can often be totally something else. (Since it's an LCD, it's probably not item #2).

Yawn. Nothing new here, I've seen it all.
/jaded

[Chief Blur Buster]

New thread created:

100 Issues Other than PWM: Blur Busters' Word on Overemphasis on PWM

PWM is one of the biggest problems, but it's but a mere slice of a 100+ Display Ergonomics Problems Pie.

So that new sticky is a must-read for newcomers to the new Display Comfort forum, and I've even stickied it. The people who failed to PWM-diagnose in other discussion forums typically invariably come here to Blur Busters (namesake as beacon), and so I've always taken interest in at least attemping to help. I don't always successfully diagnose on the forum, but I do usually successfully diagnose on-site or paid (as long as equipped sufficiently). However, I will attempt to improve my batting average in the forums. (Note, I try to limit forum use to 1 hour per day, and the holidays/family/pet will pull me away more often this month before CES 2024.)

[BFI]

I've a related question Chief: why do I find motion noticeably smoother on a DLP projector than OLED TV, both at 16.7ms persistence with similar input lag?

I've wondered about this for a long time, because I know my eyes are too slow to see the wheel's individual colors.

[Chief Blur Buster]

I've a related question Chief: why do I find motion noticeably smoother on a DLP projector than OLED TV, both at 16.7ms persistence with similar input lag?

I've wondered about this for a long time, because I know my eyes are too slow to see the wheel's individual colors.

May this become a new thread?
While I have veered off track slightly, this is a fairly large thread-topic divergence, and I want to give the original poster more control over this thread's direction. [EDIT: Thank you!]

[BFI]

Lots of forums I've used discourage new threads if there's a topical one to join, but while eye strain and smoothness perception both relate to our eyes, I appreciate the science between their explanations might be very different!

New thread started: viewtopic.php?f=7&t=12817#p100085

[Chief Blur Buster]

Lots of forums I've used discourage new threads if there's a topical one to join, but while eye strain and smoothness perception both relate to our eyes, I appreciate the science between their explanations might be very different!
New thread started: viewtopic.php?f=7&t=12817#p100085

Yes -- true. Old habits die hard. This is true that many forums want to merge all display ergonomic issues into one thread. That's stupidly silly around here, because such a giant thread is like a "All Talk About Computer Monitors Must Go Into This One Thread". That may make sense at a pets forum, or a farm horse-care forum, but we are a freaking display forum.

Anyway, replied.