What's wrong with my Ps3 being slightly loud?

Recently I've been playing battlefield 3, and every time my ps3 makes a slight high pitched fan sound. Not loud, but noticeable when I take a break. It's a Disc game and also today my ps3 randomly shut down but the green light just kept blinking! I cleaned out the dust, and everything seems smooth. Except battlefield still gives off the high pitched fan noise and minecraft exited my game a few minutes ago?

How old is your PS3? If your PS3 is an older model these problems are mostly likely due to wear and tear of some it's internal components--most likely due to excessive heat buildup.

After a while, the original thermal paste that Sony used tends to dry up and flake off. This creates an unsafe heat buildup which can lead to an increased fan noise (it needs to work harder to keep the console cool) and can also lead to console freezing issues, and mandatory shut downs.

Make sure your console vents have enough room to breathe and limit your gaming sessions. If the problem gets worse, contact Sony or a local console repair service.