Fan noise in Inspiron 5548

I bought this new inspiron 15 5548 model just 4 months ago.

And now, it is producing so much noise due to the fan. The noise usually comes after around half an hour irrespective of the no. of processes taking place or cpu load . The sound is in mostly two levels .. initially ,, it remains low but after 3 or 4 minutes it gets excessively high.

It is still in the warranty period ..  I want to know what should i do ? ... take it to the dell service center  or calling some personal technician as some people are saying that dell is not trustworthy. 

Any suggestions?