My computer is making a low humming noise does anyone know that that is. i do not know if it is serious for it is normal

my laptop is making a buzzing noise i checked everything i do not know what is wrong with it

i cleaned my fan on my G75vw bbk5 and now my laptop is buzzing i do not know what is wrong with it

can some tell me why my laptop is making a low buzzing noise i cleaned the fans. then the buzzing started

My laptop has problems with its CD-ROM drive it sometimes reads discs and sometimes does not.