PC Fan making a weird noise on start up

[Showkes]

This problem started yesterday. I turned my PC on, and it was making a weird noise. ( Something like prrrrrrr ) The thing is, when I turn my PC off and 10 seconds later I turn it back on, the noise is gone. When I turn my PC off the CPU Cooler fan is the first one that stops, and then the noise stops aswell. No cables are touching any fan.

Should I be worried about it?
Thanks in Advance.

 

[James Mason]

might just be dusty, google how to clean dust out of a computer,
could be a bad bearing, which means you need to get a new fan.