Computer keeps getting louder

Is it warmer indoors than it was before?  That can make the CPU fan run faster.  So does running demanding applications.  So does a buildup of dust after 2 years.  Clean the fan and heatsink with vacuum and compressed air.

 

By the time you 'hear' a harddrive failure, it's already happened.  Are you sure the computer is louder?  Or could the room have gotten quieter (A/C not running as much)?

 

Noise is very subjective, and computers are not silent. 

I had a Dell server recently reported as running "loud" and it was the main fan in the back starting to go bad.  (bearings maybe)    I replaced the fan and no more noise.  (could not find the part here at Dell, had to order it elsewhere)