I have HP 2570p with Intel HD 4000 and its PWM frequency for controlling screen brightness is too low for comfortable operation. It's set to 300Hz which is not perceived as flashing, but with eye movements it's very distracting and causes headaches in prolonged sessions.
I have contacted HP with this issue, since no other 12" Elitebook suffered from this issue, the technician changed motherboard and screen, to no avail. Therefore the case was elevated and HP told me to contact Intel for an utility to reprogram VBIOS and set the PWM frequency higher.
Upon checking the schematics for 2570p, the screen is controlled right through chipset, more specifically 'ITL_COUGARPOINT_FCBGA_989P' is connected to pin 16 to "INV_PWM_3".
There's Intel® EMGD Configuration Editor available for system manufacturers that allows for VBIOS modification, but not designed for QM77/HM77 chipset.
Any way to fix this?
I was told HP will not issue system board revision due to model obsolency.