AFFS displays - backlight modulation (ripple) question

[xsixt]

Out of interest can the LCD PWM frequency/duty cycle be modified in Lenovo bioses?

I have noticed on the following T60p (Hydis) / T42p (ID-Tech) / X60T (Unknown AFFS/VA), these utilise a PWM duty cycle of 100% (full brightness), thus the screen is essentially "flicker free".

However the X200/X201 (tested Samsung TN CCFL, Hydis CCFL, TN LED) series use <100% @ Full brightness, so the result is a fast modulation (flicker), and more annoying to use for long periods. E.g. the X200/X201 series flicker at 625 Hz (tested with an oscilloscope and photodiode).

I would have assume Hydis panels wouldn't have differed much, over the period from T60p - X201, so I am wondering if the modulation @ 100% is due to something else other than the panel, such as the graphics driver, BIOS or inverter?