We just purchased about half a dozen new Dell XPS 14 (L421x) laptops from Dell. I wiped out all the hard drives and re-installed fresh copies of Windows 8 x64 on all the machines.
The brightness controls do not work on ANY of the machines!
Neither the F4/F5 buttons, nor does the slider control in Power Options will change the brightness of the screen.
I installed the latest drivers from Intel version 9.18.10.3071.
None of our systems have the Nvidia cards, they only have HD 4000 on board graphics.
Intel, please help!! Not being able to lower brightness kills the battery!