Why some of the users? Because our equipment measured 19.5 kHz frequency of the emitted light. And as we know, higher the frequency, less affected your eyes will be by PWM. But if you are indeed sensitive to PWM, we suggest looking up our PWM ranking table for notebooks with better PWM rating. Or… you can just buy our custom display profiles. The Health-Guard profile will eliminate PWM and will definitely help in this regard.
You can find the available configurations here: http://amzn.to/2ugBrpV