HP Pavilion dv6 Notebook PC Making Weird Sounds

I own a laptop HP Pavilion dv6 Notebook PC and I'm having some issues.
Couple days ago, I turned my laptop on and it started to make weird noises that I never heard before.
Like rrrrrrrrrrrrrrrrrr
I turned it off and started back on and the sound was gone.
However the next time I turned it on, it was making the same noise
I tried restarting it but the sound was still there
Now every time, my computer is on, it keeps on making this annoying noise.
The laptop runs just fine though
Need some help please

 

I'm going to try to download the BIOS update.
Quick question, I seen the dl links on the stickie for dv6 with different XXXX
How do you find your XXXX?

 

Sandy bridge is 6100 and ivy bridge is 7100 i believe.

Sent from my SCH-I405 using Tapatalk

 

Ok Update
I have installed the lastest version of BIOS
However when I turned on the laptop this morning, this appeared
"Cooling fan not working properly, must reboot"
So clearly this is a fan problem
Should I take apart the laptop and try to see what is wrong with the fan (like see if there is too much dust)
But I'm not very good with computers and never have taken apart a laptop before
Also if I do take it apart, does that cancel my warranty? I'm not even sure if my warranty already expired or not
Would like any tips, thank you!

 

Yeah, take system apart and see what happens when the system boots to the fan and also clean it out.