Weird laptop fan sound

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http://askubuntu.com – I just bought a new laptop - SAMSUNG Series 3 NP350V5C-T01US, installed ubuntu 12.10. Everything is ok, except a very annoying sound produced by the fan. If it would be just a constant sound, I mean the same sound all the time, it would be acceptable. But I hear a raising and lowering sound, it seems the speed of the fan is bigger and lower, bigger and lower. The cycle is several seconds. So annoying... I have tried an opensource video driver, proprietary drivers (stable and beta). Any thought, guys? (HowTos)