Hey well i have dell inspiron 15 5000 series. My built in Os was linux. Sometime ago i  installed windows 8.1 snd dan i stated having this problem that my brightness couldn't get controlled thru either f11 f12 buttons or with brightness bar not even with on screen keyboard. Only i could change it in bios. Someone asked me to check drivers and i had microscft basic driver along radeon graphic driver bt no intel driver. I tried to install intel bt evrytime it gave error that my system doesnt match the minimum requirement. So i am basically stuck with this problem.  Plz help me out.