Last updated: 08/10/2024 All future testing beyond the results in the table will be done with ThorLabs PDA100A2 photodetector as it will likely pickup even minute levels of PWM type flicker. After the latest Windows 11 update to build 22631.3155, I now see significantly more pixel level flicker on the Legion 7i, T480s, and on the LG 27gp95r-b monitor. Still testing... Update: As recommended by @jordan , using Windows 10 1809 (with a manual OS update, instructions below) has led to improvements. Using intel iGPU for T480s and 7i results in significantly less pixel flickering regardless of screen refresh rate (60Hz, 64Hz, or 240Hz). If using the Nvidia GPU on 7i with latest studio driver on 1809, I still see flickering with the screen is set to 60Hz but less so at 240Hz. Installation for Win 10 1809 for T480s and Lenovo Legion Pro 7i: Win10 Iot Enterprise LTSC 2019 (Build - 17763.107) en_windows_10_iot_enterprise_ltsc_2019_x64_dvd_a1aa819f.iso <[removed by moderation]> You may have to set secure boot to off for successful installation. Manually update with this version after installing with the previous iso. https://www.tenforums.com/windows-10-news/152009-kb4538461-cumulative-update-windows-10-v1809-build-17763-1098-march-10-a.html Microscope Videos (240 fps played back at 30fps): https://www.dropbox.com/scl/fo/47fw3ygxkxaq78ul0j19i/h?rlkey=a2fvkmlujs2m9tkmdw59ujwvl&dl=0 Hello folks. I am in the process of testing panels for pwm using Miniware DS213 oscilloscope and BPW34 photodiode + Opple Light Master 4 and temporal dithering and/or pixel inversion with high speed phone camera (240 fps) and microscope (carson microflip at 100-250x magnification). So far: Device Panel Model # PWM Dithering (or pixel inversion) OS Lenovo Legion 7i Gen 8 (Nvidia RTX 4080, 2560x1600 matte IPS) NE160QDM-NZ3 (BOE) Opple: 0.0141 Flicker Index, 7.61% Modulation at 50% brightness 33425Hz None detected with Miniware Yes (in 60hz mode), Higher frequency dithering less detectable in 240hz mode) More comfortable for me but YMMV Window 11 Home 23H2 Build 22631.2861 Thinkpad T480s (2560x1440 matte IPS, Intel UHD 620) LP140QH2-SPB1 None detected with Miniware, Opple: 0.0171 Flicker Index, 8.97% Modulation, 36342Hz at 52% brightness Yes (also with B140QAN02.3 ) Apparently after re-testing both panels show dithering so the T480s is no magic solution. B140 panel seemed to have less pixel dithering. Windows 10 Pro 22H2 Build 19045.4046 Thinkbook 13s G3 (2560x1600 matte IPS, AMD Ryzen 5600U) N133GCA-GQ1 None detected with Miniware Yes All (windows 10 potato edition linux mint xfce…) Nothing worked including ditherig, etc. 🙁 UPerfect 18 inch 144 hz 2560x1600 IPS portable display N/A None detected with Miniware Yes just less noticeable due to higher refresh rate Windows 11 Home 23H2 Build 22631.2861 (tested using nvidia 4080 laptop gpu via usb-c) Eizo ColorEdge CS2740 N/A ? Yes (both 8 bit and 10 bit modes) windows 10 potato edition (ryzen 5700g iGPU via HDMI, nvidia quadro k4200 via displayport), windows 11 23H2 (tested using nvidia 4080 laptop gpu via usb-c, hdmi) LG 27gp95r-b (not recommended due to panel horizontal line artifacts after less than a year of use) N/A Opple: 0.0089 Flicker Index, 4.53% modulation, 34008 Hz (144Hz, 35% brightness) None detected with Miniware (update: yes with thorlabs detector at 20dB gain: https://imgur.com/a/Vc4SVzk ) Yes just less noticeable due to higher refresh windows 11 23H2 (nvidia 4080 via usb-c) The older Thinkpad T480s seems good and never had problems with it. The Eizo also has a rougher matte surface that may be a problem for some. For the uperfect display I could not see dither at 144hz but not sure at 60hz setting. Given the limitations of equipment and threshold at which PWM may still exist, these data are considered measures of relative safeness of the tested devices. For devices with Nvidia GPU, I used their latest studio drivers and also the latest graphics drivers from AMD for the ThinkBook. For the Eizo I was not able to get clear info on whether it was true 10 bit or 8 bit + FRC. These two sites show conflicting info? I should also mention that I also used novideo_srgb and ColorControl but was unable see a difference after setting temporal dithering to disabled. https://www.displaydb.com/monitor/eizo-cs2740 https://www.displayspecifications.com/en/model/21d01e78 I also tested the keyboard backlight of the 7i and T480s. I did not detect any flicker from my T480s. The 7i keyboard light flickers intensely at low enough frequency to be visible in normal digital camera video at 1/8000s shutter speed. To be safer, I would recommend not using keyboard backlighting at all and focus on increasing your natural workspace/living space ambient light levels. The Opple Light Master 4 results seem promising. However, when doing repeated measurements, the reported frequency changes widely from high 30K to low thousands or occasionally even low hundreds for all of the tested panels. However, the results are always reported as "no risk". This is consistent with other's findings about the limitations of the Opple Light Master. 7i Color Rendering Index (CRI) at 96%? Light Master report on 7i laptop internal display measured at 100% brightness on pure white. The CRI is reported to be high at 96%. However the default color temperature of the display is way too blue/high at greater than 8625 Kelvin. https://iot2.opple.com/lightmaster/index.html#/report/01f5aa1814f8481f97d475d204dec4be ~~~~ 7i spectrum measured using HPCS-320 shows Ra of 87.9 and CCK (K) of 6427.

A couple of tips, (1) Isn't it easier to go to the site notebookcheck.net read reviews for laptops? (2) Intel iGPU is responsible for displaying a 2D picture (desktop) in a laptop. Hence the dithering in 1440/60Hz mode. Just disable the Intel iGPU and the problem will go away. (2) Only the IPS matrix does not have pixel flickering? Do not buy laptops with other panels. (3) The problem with the Intel iGPU is not only forced anti-aliasing (pixel flickering), but also de-synchronization ( Input Lag) of image output to the monitor. After turning on FreeSync Premium the problem is solved.

AlanSmith Yes, I know about notebookcheck for many years. It would be easier but I had access to these devices before discovering this site only recently and recognizing symptoms. I have tried HDMI, displayport, usb-c, and from nvidia 4080 and hdmi from ryzen 5700g iGPU to the Eizo and I can still measure dithering even when output is set 8 bit mode to avoid potential 8 bit + FRC feature. I also tested a quadro k4200 running on windows 10 potato edition via displayport and still see dithering. I no longer have the Eizo but I still think it is more likely my gpu/ software combination doing the dithering. For the legion laptop, I have the igpu disabled in bios for testing all external monitors. In NVIDIA control panel, I have tried both 8 bit and 10 bit output. I have tested two T480s both running on intel 620 igpu, same screen specs, same os build versions and drivers, but different panels and differing dithering results. I do this in case it is helpful for others and I do hope more review sites provide more testing beyond just backlight flicker. Based on posts on this forum, it looks like dithering depends on a combination of software (OS, drivers), video card model and the firmware/bios, display, and perhaps even sample variation from manufacturing defect but I not sure about that. For the uperfect, I tested using usb-c at 144hz. If I understand correctly, others are saying dithering is "baked in" to these newer nvidia and amd GPUs now. No idea what AAS matrix is. Still looking…* * https://ledstrain.org/d/2460-ah-ips-ips-ahva-ads-aas-my-experience-with-different-lcd-panels

photon78s For the Eizo I was not able to get clear info on whether it was true 10 bit or 8 bit + FRC. These two sites show conflicting info? An internal source of mine at EIZO claims the CS2740 is true 10-bit. However AFAIK even if it was 8-bit+FRC, in theory feeding it an 8-bit signal would still be okay.

JTL Also I forgot to mention. Same source claims CS2740 is flicker/PWM free.

AlanSmith And notebookcheck.net does not do temporal dithering measurements for all devices. Disabling intel iGPU in bios resulted in no visible change under the microscope. On the Legion, the 240 hz setting can be enabled while the nvidia GPU activity icon shows no activity. As someone still doing and learning 3D web graphics programming, 240hz is only a slight inconvenience for clients but that's another issue for another time. An old arduino demo of dithering (what is the frequency of these algorithms?) https://www.youtube.com/watch?v=1-_JtRl2ks0

photon78s You understand, manufacturers are increasingly lying that the 8bit panels (although in fact they are 6bit + FRC). There should be no dithering on honest 10bit. You can check your monitors/laptops on Android x86 (for your computer). You can install Android 13 X86 (Gapps) on a USB flash drive through Rufus . And run as a LiveCD without installation. Will there be dithering/flickering on 6bit. Or is it a panel problem?

So is the Legion 7i Gen 8 considered comfortable at 240hz then? I'm curious about if the OS could still cause strain even without pwm/dithering

jordan So far so good (a few weeks) using the 240hz internal display and the uperfect montior at 144hz connected using usb-c /nvidia gpu. YMMV. OS/drivers/software/accessibility settings could all matter. So much discussion of that on this forum already. And their is also the panel lottery situation as well. I one point I tried using an usb capture card connected an e-ink android tablet as a DIY alternative to dedicated e-ink monitors for text only work but it was way too slow, bad contrast, etc. Those dedicated e-ink monitors also still have a long way to go but seems to work for some.

photon78s that's great! Maybe I'll consider trying one if my PC I'm building doesn't end up working for me.

jordan FYI, the keyboard backlight flickers on that laptop.

Products to try or avoid? PWM Flicker and Temporal Dithering Testing

jordan

photon78s I'm not quite sure what pixel inversion is but I'll read up on it! Wow even the same panel could be different?! That's crazy ugh

jordan

photon78s is there any devices that have not even the slightest movement? None at all?

photon78s

jordan

I can say that the 7i and the lg is so far working for me.

https://www.lg.com/us/monitors/lg-27gp95r-b-gaming-monitor

Check out videos of the 7i flicker and lack of flicker at 60fps versus 240fps screen refresh rates. Taken with microflip and phone camera.

https://www.dropbox.com/scl/fo/rvv910m63ihinexn0dvmc/h?rlkey=s5yh04fw0rew3jx48lthrkkyj&dl=0

jordan

photon78s wow that's great! I didn't look at the recordings because when I look at certain patterns with colors(pixels being one of them) it makes me really dizzy nauseous right now. So 240Hz is better then?

Any thoughts on the Samsung G8 OLED monitor?

photon78s

jordan

Yes, 240Hz is better for me, same with 144Hz on the LG. I don't use 60Hz anymore. The recordings show clearly that at 60Hz "mode", the pixels are flickering/changing. For both recordings, the screen was set to 100% brightness, only the refresh rate was changed and the microscope was looking at the same general area. No idea about G8. I think others on the forum have experience with oled monitors.

jordan

photon78s oh that's the IPS lg I just noticed. That's great that it doesn't flicker. I have some stuff I need to test but if all fails I'll have to try some of the stuff you show is safe. My other concern is if polarization plays a role too with screen issues.

jordan

photon78s is it the legion 7i pro ? Can you send a link to the exact one you have? Im thinking to try one if I can find a used one for a deal.

photon78s

jordan

Glad this post could be helpful. I would caveat that by saying safe to this limits of my measurement and personal physiology, stress levels, etc. One thing, I would hope more people on this forum would discuss is how to improve "immunity" or "tolerance" to these less than perfect devices.

I took out some old polarized sunglasses. The 7i is black when looking through sunglasses rotated 90 degrees vertical. The LG is black when looking through sunglasses normally, horizontal. I think this is common for screens to differ like this.

jordan

photon78s All your info has been super helpful and I always am checking to see what new devices you test and what you say about them! haha. I wish I could do the same but with how severe the neurological symptoms I get I just can't go through testing a lot, I will eventually test what I got here though. I got a bunch of GPUs and monitors to go through. I will say that my doctor said his patients were able to return to screens after stimulating the trigeminal nerve with either a medication or a electric tooth brush for a few seconds on each side of your nose. Maybe the tooth brush thing might be worth to try for you ? Doesn't always help everyone but if you have one, might not be bad to try. He said that the nerve has to send and receive at the same rate otherwise people get issues with screens. Maybe the flickering makes the brain go bonkers if the nerve is having issues ? Maybe that's what stimulating helps with ? 🤔 Regardless I still would prefer zero flicker even if that was the issue

photon78s

jordan

The trigeminal nerve stimulation is interesting. Need to learn more.

I have this from b&h on discount:

https://www.bhphotovideo.com/c/product/1745683-REG/lenovo_82wq002rus_16_legion_pro_7.html

However, as you know, the manufacturer may use a different panel just with the same general specs.

jordan

photon78s yeah the stimulation could be something that could help.

Thanks for the link. I got a deal on one used so will see how it's like and what panel it has when I receive it. I saw you also have a k4200, is that safe when paired to a safe monitor ?

photon78s

jordan

I read on this forum that a k4200 is safe. However the one I had and later returned did not change the pixel flicker on the monitor side under the microscope. I was also using displayport, and trying novideo_srgb and ColorControl to try to disable the dithering. Of course, if I am measuring pixel inversion and one is sensitive to that, then the problem lies on the monitor side and changing the gpu would not help.

In your situation, would another solution be simply using a high refresh external monitor like the lg or the portable monitor work connected to whatever computer of your choice as long as the computer can drive the monitor at desired refresh rate?

This another forum member's pixel inversion video. The flickering is different from what I captured using the microscope and high speed camera.

https://www.youtube.com/watch?v=4H6bETUx2Lc

Just adding this for reference: pixel inversion easily confused with temporal dithering and vice versa:

https://www.displayninja.com/pixel-walk-pixel-inversion/

jordan

photon78s do you mean that it still had dithering regardless when you tested with that GPU? I'm not quite sure if it's pixel inversion or dithering I'm sensitive too but I'm pretty certain it's the dithering. Sounds like a high refresh rate monitor could help mitigate the dithering.

My 7i pro comes in tomorrow according to tracking but will test it once I come down from a flareup. Any settings to enable/disable in bios/windows/driver? Did you use colorcontrol or disable igpu in bios?

Thanks

photon78s

jordan

Yes, I still saw pixels changing no matter what software or gpu I used. The K4200 also has limitations in supporting high rez and high refresh rate.

For the 7i I am running with out of the box settings (no colorcontrol and no color management profile set). GPU is set to dynamic graphics in bios. Most importantly, screen refresh set to 240 Hz.

photon78s

Also, I have HDR turned off but not sure if it matters. Laptop display usually used at 50-70% brightness.

photon78s

I tested someone's NEC EA271U and it has pixel flickering connected to the Legion 7i via usb-c and running on nvidia gpu. It has this "human detection" feature using IR sensors on the bottom bezel and after around half an hour, I felt a sense of "warmth". Would disable that feature if I was using it long term.

Specs:

jordan

photon78s that's so weird how some monitors are safe like the uperfect and LG but then that nec one isn't. I wonder if color control would have any affect with the nec?

Also thanks for letting me know if the 7i settings. I'm hoping it ends up being somewhat comfortable I have no PC right now that works for me.

IR would be something I would disable on any device for sure haha.

photon78s

jordan

The nec is only 60Hz and I suspect it uses FRC. Red light therapy is a thing so the different frequencies and energy can be used for "good". Hope the 7i can work for you1

jordan

photon78s oh that makes sense then seems like 60hz could be the more problematic thing. That's true about red light I just wonder if IR face/eye sensors is strobing or is emitting a ton of light that makes it not so good sometimes. Thank you! I really hope so too. I'll post how it works for me when I test it.

jordan

photon78s can you post the link to the uperfect you have btw?

photon78s

jordan

https://www.amazon.com/UPERFECT-Portable-2560x1600-FreeSync-Frameless/dp/B0C7Z3ZY3P/ref=sr_1_1_sspa?keywords=uperfect%2B18%2B144hz&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

I returned it as I needed a bigger display. Still currently trying out that lg I linked above. I didn't feel any particular strain during the few weeks I was testing the uperfect. How is the 7i?

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