fans have become louder

For some reason it sounds like my fans have become louder within the past day or so. I have done all the usual cleaning with air compresser, cleaned out dust, checked the fan speed. All fans are running at 1962 rpm to 2008 rpm. I am unsure what is a good fan speed. I am on windows 7 64 bit. My CPU is intel core 2 quad. Its an asus computer. I would really like some help with this as it sort of concerning me. Any help would be greatly appreciated.

 

thanks for the reply. Yeah, I have checked the temps on everything and everything is super cool. nothing on the temp side is out of place.