Problem with Fan Sounds

Hey, today my PC started to sound like Arnold. No joke, it sounds like i'm next to a flight engine. What would that cause? Nothing is different after all, everything runs prefectly however, the sound of the PC is making me a little bit nervous. Might be fan? I have no clue.

You should probably go into your BIOS and fix it. Any programs running that you don't want on?

Uh, what does this have to do with fan sounds though? I don't think any unwanted program is running right now.

Could also be buildup of dust. You could try cleaning the inside and see if that helps.