Maxx
I tested the X1 Carbon 4th gen (2016) with FHD display resolution for about 2 weeks a while back, using it as my daily work laptop in the office. It came with Windows 10 version 1511. This laptop has no PWM. Notebookcheck also confirms no PWM in their review for the FHD version. Using the laptop on Windows 10, I get very very mild eye irritation/strain, which I contributed to the intel graphics driver. Using the laptop unplugged (on battery) somehow makes it better, although not 100% eye strain free. Using Windows 10's Microsoft Basic Display Adapter is about 99% eye strain free. I would not call it completely eye strain free, but I feel there is still something there. I tested this configuration for a week.
After the first week, I asked my IT department to install Windows 7 Pro on this X1 carbon. Used it for about a week as my main work laptop. Similar result. When I use the Standard VGA driver, no eye strain, but the brightness would go up to 100% and there is no way to reduce the brightness when using Standard VGA driver. Plus every time I want to switch back to the intel drivers (to use projector etc), I have to restart laptop to change the driver, which means I have to save and shut down many office apps that I have running. Not practical, so it was a no go for me.
I have not tried Windows 8, but this is something that I will try, because last time I tried this windows (a few years ago), can switch graphics drivers without needing to restart. Plus the Microsoft Basic Display Adapter is also generally faster compared to the Standard VGA driver from the Windows 7 Pro.
I like this laptop because this is the first laptop that I have tested that does not have any PWM. The other cause eye strain, is caused by software, and I can use some workarounds to manage it.
I wanted to order the X1 Carbon 4th gen, as this is the model that I have tested, but the supplier suggested to go for the 5th gen X1 carbon FHD version, as the 4th gen is old model and difficult to get stock. I checked the notebookcheck.net review and the 5th gen X1 Carbon FHD has no PWM. So I agreed to get the X1 carbon 5th gen. It is being ordered now. Once I get it, I will test it using the Windows 10 that comes with it, then likely will install Windows 8 first and see if I can use this in practical manner. Last if all does not work, will install Windows 7 Pro.