Hello,

So I have read through most of the posts here, including the one where someone got rid of eyestrain due to using a correct ICC profile on his monitor.
I have noticed a very interesting thing - I am using an old ACER laptop (no eyestrain there) connected through VGA cable to ASUS PB238Q monitor. The monitor is LED and from a time where noone cared about PWM, so it definately has it.
What is funny though, when I use it connected via VGA I get no eyestrain and the monitor is really nice to look at. However when I connect it through HDMI I do get eyestrain. I can tell the difference within seconds.

Does anyone have similar experience, maybe something in the way HDMI is processed vs. VGA? Or maybe since VGA is older and more noisy, it can cancel out PWM or lessen its effects?

Also, I cannot find anywhere some standard color ICC profile for the monitor, so I guess I cannot test whether that helps or not. However the VGA connection also wasnt calibrated or played with and is set "as it came".

Thank you for your input on this.

I want to add that the HDMI picture indeed does look different and with this test http://www.lagom.nl/lcd-test/black.php the VGA shows more blacks, while the HDMI shows the first few squares completely merged with the background.

VGA runs through a DAC. Then back through an ADC.

HDMI has neither.

So what you're getting with HDMI is a ... "less processed" image, but also more opportunity for the OS, hardware, or display to decide to "modify" it.

Thank you. Is there any way to simulate the VGA processing on computers that only have HDMI ports? I bought a HDMI to DVI (HDMI connected to computer, DVI to external monitor) but it looks the same as if it was only HDMI on both sides.

For the record the laptop is very old and I run the external display on the laptops AMD card. Therefore the problem shouldnt be connected to any Intel drivers. Only PWM of the external monitor or the dithering of that same monitor, that gets cancelled or altered due to the VGA cables processing.

Look in your drivers to see if you can change the HDMI port's levels from/to PC 0-255 and Video 16-235. The squares merging are indicative of black crush and that the output is currently set to video.

Continue using the VGA cable if it works fine.

That is a very useful advice, please how would I find such info? I am using it on Windows 7 (edit - I have found a link describing on both AMD and Nvidia how to do it, I will try it next time I am at the external monitor - for anyone else having this problem, here is the link https://pcmonitors.info/articles/correcting-hdmi-colour-on-nvidia-and-amd-gpus/).
Id love to keep using the VGA, but I need a new laptop due to this one getting obsolete, and new ones only have HDMI connectors.
By getting and then (due to eyestrain) returnign new laptops I discovered this whole PWM/driver/etc eyestrain issue, now noticed it happens even on older setup with HDMI cable.

4 years later

Are you sure it's not due to full RGB with the VGA? Many times HDMI defaults to Limited mode.

I'm looking at a new refurbished computer for myself and wondering if I will be fine with 1 VGA outlet and 1 displayport or if I need both outlets digital. That's how I came across this post suggesting VGA improved the experience for him.

  • uizz replied to this.

    Found this as well:

    Upgraded to an HDMI video card and this monitor from a VGA. I was expecting to really enjoy the difference. Instead, I get eyestrain just looking at the screen for ten minutes. This is the brightest monitor ever, and I've even put the brightness down to 20%. I've tried all the tweaks that are built in to the monitor; tries the windows tweaks and the NVidia tweaks and nothing helps. I've been trying for a few days. The words and images aren't crisp. Movies look good and vibrant, but details aren't sharp. I'm definitely sending this back.

    K-Moss i tried every pixel format, full, limited, ycbcr444, ycbcr422...i even buyed a new hdmi cable, but nothing seems to help 🙁
    Only vga is safe for me (same gpu, same monitor)

      uizz Yes, and I wonder how many others would be benefited by VGA even if we don't understand why. In the review I quoted above, she said she got the worst eye strain ever when she "upgraded" from VGA to HDMI. I omitted the title saying that.

      Has this issue been seriously explored here? It could also be linked to why people think the old non-LED backlights are more comfortable because we always used to use VGA.

      • uizz replied to this.

        K-Moss don't know but i also think this could be the solution.
        Would be nice if someone made some scientific research with tangible proofs, I tried with my phone camera but I couldn't find any difference.

        So has anyone here taken a problematic monitor, used a digital to VGA adapter and used the VGA on the monitor, and seen if it helps? I've ordered an HDMI to VGA adapter to try it myself. In my case my current computer doesn't have a VGA out, but most do, so for most you should be able to use a VGA cable without any adapter. All my monitors have VGA inputs.

        I'd also be very interested in hearing if there's anything to the HDMI to VGA angle...

          AgentX20 Ive spoken with some people from the local hacking and tech community and they explained to me that it makes sense. The analog nature of VGA really washes and smoothes out any harsh dithering flicker.
          But as we know - not always and not all the same. I guess it depends on input.

          Ok so I tried connecting my windows 7 laptop, which never gave me eyestrain through VGA, with a displayport->DVI adapter and bam eye strain and nausea.
          This is incredible....I don't know if it's my monitor (Benq GL2250HM) but I can't use it with anything other than VGA.

            uizz The adapters are not all the same. Different chips in them and the microcode to run them will produce different output. I have several adapters here and there are subtle differences here and there.

            My NUC has a DP output and a HDMI output, but what most people don't know is that on newer machines the HDMI output is actually an internal DP-to-HDMI adapter.. so in my opinion it's generally better to just use a chosen adapter for DP to whatever. Older machines had native HDMI output or native VGA output.

            There will be DP-to-HDMI 2.1 adapters this year. Worth trying then. 2.0's are out but might as well wait since you have a working VGA solution.

            The only time the VGA solution does not work well for me on my hardware is with protected streaming video. On Amazon, for TV shows it doesn't care and will give you full resolution on VGA on 7, but for movies it cares a whole lot and will lower the resolution/bitrate. On Netflix it cares for both shows and movies and in addition, requires windows 10 to get full bitrate (this means even if you are using HDMI on 7, Netflix will limit your resolution and bitrate). Because of this (and also because my monitor is on an arm now and my vga cable was 1.5 feet or something) I started using the HDMI port on the monitor for now.

            It may not be your monitor, it may just be a poor quality adapter, but there is one additional thing you can try.. there is a possibility your monitor is using a different chip internally for the DVI port than it is for the HDMI port, so in that case, what you could do is get a DVI-to-HDMI cable and try the HDMI port with your existing DVI adapter. It will work because the DVI and HDMI video signals are 100% compatible. You won't be able to use all the HDMI options with a DVI adapter on the HDMI port but the video will be there. A cable with a DVI connector at one end and HDMI on the other is cheap because it's just a cable, no chips.

            Incidentally, I have an old HDMI to VGA adapter cable that strips HDCP (intentionally). I tested it out and it does work to stream movies over VGA, but the problem is that specific adapter is locked into limited range and I have no way to change it to full range since it's set in the internal hardware. I would have to use a color calibrator to compensate for the range change but I don't have a calibrator. It's another option to consider of course.

            9 days later

            What about using 2 adapters: hdmi>Vga vga>hdmi?

            9 months later

            I had never looked at HDMI vs VGA cables as potential triggers. Now something puzzling happened. All of a sudden I got awful long-lasting symptoms, such as eyestrain, neck tension, blurry vision and headache, after shortly looking at the monitor of a shared computer that did not use to give me trouble. I checked all the settings and nothing was changed. Finally I figured out that the HDMI cable was replaced from this type to this other type. Looking at the specs of one and the other as a non-expert, the only difference I spot is that the new cable is supposedly of higher quality and "4K".

            Has anyone experienced surge of symptoms by changing the HDMI cable? I could test a bunch of the new versus the old and see if it is systematic or just a one-off bad cable. I wonder because I read a review in which the author says that there is no reason to buy expensive HDMI cables as they make no difference whatsoever.

            Thanks in advance for any insight!

              AGI

              The fancy cable will have a higher data transfer rate, conversely the cheaper cable will have a lower transfer rate. Not sure what the visual implications are of running a low spec cable though, I had assumed it just wouldn't work, but I wonder if your monitor was running at a lower framerate or resolution or something?

              • AGI replied to this.

                HDMI cables are not active converters. They're just a cable carrying a digital signal. Skeptical that this cable means anything, however simply put the old one back in as a test, it will work for hdmi 2.0 too.. the specification requires both the display and the device to support the 2.0 protocol and the old cable you listed was already listed as supporting 4k, deep color, etc. It will work just fine with 2.0.

                • AGI replied to this.
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