The ThinkPad T, X, and P families are home to Lenovo's more well-known models including the 14-inch T480, 15-inch T580, X380 convertible, and 15-inch P52 workstation. While their design, features, and performance are generally very well received, many may be unfit for users who are sensitive to flickering lights. Be wary when purchasing the following ThinkPad models.
https://www.notebookcheck.net/Sensitive-to-onscreen-flickering-Take-caution-when-purchasing-these-Lenovo-ThinkPad-SKUs.309634.0.html
Hey, thanks! I'm one of those who affected by pwm.
Not at 900Hz or more you aren't.
Your eyes, no one's eyes, can discern changes in brightness that quickly. Not even close.
Very, very few people can see brightness changes at 60Hz. Forget about 100Hz. 900+Hz is right out.
Doesn't matter the speed of flickering, I am affected by PWM even on the new MacBook Pros, which flicker in the 23,000Hz range (or something like that).
You don't 'see' it, you don't even feel it instantly, you just start to feel like there's something wrong with your eyes after a half hour or so, and it seems to get worse on repeat exposures, so that eventually you DO 'see' it as soon as you look at the screen -- or more 'feel' it as 'woah I can't look at this, this hurts my eyes'.
I had to return my iPhone X for the same reason (which i didn't even realize had PWM until i found after a couple of weeks that i just couldn't look at it any more, and subsequently discovered all OLED has PWM), and am back on a non-OLED iPhone 8 now.
If PWM doens't affect you, lucky you. But it's real at any speed for those of us it does affect.
Thank you very much, great information!