Fan speeds up and slows down annoyingly on a Dell Latitude 5520

view full story

http://askubuntu.com – I' ve just bought a dell latitude 5520 and installed 11.10, my trouble is that the fan is noisy which is not regular. It is quiet for 1 minute and then speeds up and slows down every 4 seconds for 1 minute : it's very annoying. I tried i8fan things on the Internet but i didn't solve my problem, it seems to work better in windows 7 but i don't use it a lot. Dell technician came and changed the motherboard and the fan but it's still the same. I have to put music on when i'm on my computer... Anyone have the same problem or a solution? (HowTos)