Computer fan running hard...

[Mockery]

My computer fan is always running fairly loudly these days. First off, it's an Antec Sonata case, so it's supposed to be really quiet, but this fan is always running loudly. Furthermore, if I open a program like photoshop or even outlook, it runs extra hard to the point that I swear the thing would lift off into the air and fly away if it ran any harder. :o

Any ideas as to what could be causing it to run so hard? I mean, I understand the need to run a little harder, but it seriously sounds ridiculous sometimes.