Hello everyone,

I have a Thinkpad T440 laptop with Intel HD4400 (I had Ubuntu 20.04, but now I'm using 16.04) that gives me eyestrain and headaches and leaves me with discomfort and even a strange feeling in the chest.

I turned off EFI in the BIOS and that seems to have made the screen more comfortable to look at. But I still get discomfort/eyestrain/headaches if I use it for more than an hour or two. I blacklisted the i915 driver (couldn't turn the screen brightness down), but the image on the screen did seem more stable, but still uncomfortable. When I turned off graphical mode in GRUB it was uncomfortable to look at - even more uncomfortable than using i915. When I go into the BIOS, the screen is also slightly hard to focus on.

When I connected the laptop to a CCFL monitor that has never given me eyestrain in the past, it is also uncomfortable to look at.

The laptop has a 2020 version of the BIOS. If it were possible to downgrade the BIOS to a 2013 version, could this fix the problem I'm having?

Otherwise, what else can I try to fix this problem? The problem appears to be present in the BIOS screen too - can the BIOS screen be affected by the Intel graphics drivers or is it totally separate to them?

Is the Intel iGPU dithering even in the BIOS? Could using Windows with ditherig.exe be a solution?

I tried using Windows 10 with the Microsoft display driver but I couldn't adjust the brightness and it gave me nausea. I haven't felt nausea like that since I used a Surface 3. I could try reinstalling and use the Intel drivers with ditherig.

Could someone please help me?

It could be the bios update has changed some other settings, you'd need to rule out other issues first such as when this issue started, do you need glasses / new glasses etc etc what about PWM from the screen? The '40 series does that I think (at least my t540p has PWM below abouny 50% brightness)

Unfortunately though there isnt always a 100% answer for this sort of thing. Personally I had a T460 and swapped the screens with my other 'good' laptop and it was fine on the 'good' laptop but (each screen) never on the t460, I had to sell the 460 as I Couldnt use it. - my good laptop has the original 2016ish bios with a HD530

What I would do is first go back as far as you can on the intel drivers, then test. (this may take days if it affects you badly) then revert the BIOS as far back as you can and test again. I did this on my 460 before I sold it and it didnt help as I could only go back so far on the Bios. IF that doesnt help then your option may be you need to put up with the discomfort (probably not a good idea) or sell it and try to get something else.

I also have a T540p, above 50% brightness its fine, below this it has PWM so it flickers and causes problems. This also has the 4400 (I believe) but the BIOS has never been updated.

Thanks for responding.
My T440 has a 2020 BIOS and it can't be downgraded as far as I know.
I'm now using Windows 10 2015 and I've removed the spatial dithering with ditherig and set the PWM to 1200 (I don't know if the PWM setting is working). With this setup the screen is definitely more comfortable than Ubuntu 16.04 (XFCE or Unity) and Ubuntu 20.04 (Gnome, KDE). But I'm still experiencing discomfort. The screen seems to pulse/vibrate ever so slightly and I can't focus properly. The same issue is present when looking at the BIOS.

Your experience with your T540p makes me think my T440 would have been more usable with the 2013 BIOS. Does using an external monitor with your T540p help at all? I can connect the T440 to my 2011 Toshiba TV and watch films without discomfort. I'm not sure why this is.

Given you are affected when looking at the bios screen, I'd be tempted to blame LCD inversion. LCDs work by applying a voltage through liquid crystal to change its shape. But, allowing current to flow through that liquid crystal will quickly destroy it. So the voltage polarity switches every other frame. This creates a flickering effect similar to dithering. There are different ways to apply inversion to disguise the flickering effect, so I would guess the implementation on your laptop affects you.

This is explained in the link below, along with some tests. Though be aware the information on this page is very old and may no longer be current.

http://www.techmind.org/lcd/index.html#inversion

If it is inversion that is bothering you, there is nothing you can do but use an external monitor. I know you said about connecting an external monitor and not getting on with it but I've had similar unexplained issues in the past. As a sanity check: do you still have issues using either screen when under entirely natural lighting? can you plug the external monitor into a different device and have it be perfectly usable again? I only say that as the monitor I am using right now is only ok with good lighting and when plugged into a specific nvidia graphics card which dithers. I falsely blamed a lot of intel graphics cards for causing me strain before I realised that.

EDIT: just read your display has PWM, that'd be my best guess for the cause of all this.

    9 days later

    Thanks for your reply, Seagull.

    I've been using the T440 with Windows 1507 with my 2009 Viewsonic external monitor (with FRC) for a few hours per day. I haven't been getting any headaches or serious discomfort. I would rate this setup as "usable", but not perfect.

    I tried Windows 1903 and 1911. On the internal LG panel with ditherig enabled there was no dithering, yet sometimes when I opened new windows the visible banding on the desktop image would move for a few seconds even though the desktop image is a static image. So I downgraded to 1507.

    I also tried a t440p with a 2015 BIOS and 2015 Intel driver for HD4600. It has a much better internal screen than the t440 (although when I tried using it for two hours I got twitching in my left eye), but I will probably be returning it for other reasons. The t440p and t440 both have LG panels but the t440p is 900p instead of 720p. The problem definitely could be something to do with inversion since the t440p is much more comfortable to look at.

    I don't think the problem on the t440 internal panel is PWM. It is even more uncomfortable at 50-100% brightness than at 10% brightness. The t440p is actually somewhat comfortable at 40-50% brightness during the day (at least when used for 10-20 minutes).

    I also tried Mint Debian (the latest version) and it seems better than Ubuntu 20.04 and 16.04 on both screens. I may eventually swap to it since Windows 1507 hasn't had security updates for quite some time.

    You also mentioned elsewhere you have a recent Dell Latitude that you can use. Can you use its internal screen for more than a few hours comfortably? Is it good on your external monitors?

        orangepeel

        I've seen the banding shift using ditherig on laptops too. I can't explain your experiences when plugging the external monitor into different laptops.

        I can't use the internal screen on my dell, but I can't use any laptop screen, or any IPS screen either. External monitors seem fine, and there is no dithering on the graphics output.

            Seagull

            For me the banding shifted only when using Windows 1903 and 1909 but not with 1507.

            Is there no dithering on your external monitors because they are true 8 bit or lack FRC? Are they CCFL? Have you had any good experiences with smaller external monitors in the 14-15 inch range?

                orangepeel

                My external monitors are 6-bit and use FRC, but it doesn't bother me. I generally find dithering on external monitors to be ok. I think that is because it implemented much better than on laptops. An external monitor can use a dedicated dithering chip, whereas a laptop will have to use its GPU to dither. They are LED backlit.

                I have not tried any small external monitors, but they are likely to be bad. They will probably use line based pixel inversion to save power, which I suspect is why I struggle with internal laptop screens.

                  Set the screen brightness to 100% to see if now PWM helps. You can detect PWM with a DSLR by taking a video with Manual Setting at 2000-4000 shutter speed. If it flickers, it has PWM and it will irritate the eyes, if you are PWM sensitive. Many screens do not have PWM at 100%, so 100% brightness gives me no strain at all. This is exactly from several Lenovo laptops that I've owned.

                  dev