Pressuming that you have had this laptop for a while im guessing that you havnt cleaned it out.
take the battery out
Unscrew the bottom panel of your laptop; pull the dust out, use a cotton ear swab and clean it out, give it a blast of cold air (hair dryer, compressor or can of air)
notice the difference....
Also please bare in mind laptops are machines what need care to function well.
Clean it out once a month atleast.
DO NOT USE IT ON YOUR LAP (irony?)
Use it on a flat surface either mesh or smooth.
Fans in your laptop WILL get louder the longer you have it nothing stays the same.
If this is a relatively new laptop and all of the above text is not valid then take it back to the store.
thanks
sig