Hey, i think Off topic is the best place for this question.

My desktop (Hp Pavilion a6450.is) been running great for 1 and half years, but lately it randomly makes a very loud Whoooooooo sound for like 30 seconds then stops. Then starts again after like 3 hrs, it's almost as loud as hoover sound, and i can feel the strong wind it blows.

Is that normal? should i worry about it or not?

Can't send it to hp care point because my warranty expired 5 months ago...

Thanks.