Laptop fan going crazy for no reason

[toutougroup96]

Greetings,
I have an ASUS TUF FX504GD and recently I've been experiencing fan noise increasing SOMETIMES here is what I know:
-When that happens (even in the bios screen) it says that the fan is spinning on 2500RPM
-The laptop has 2 fans but only the fan on the cpu side does that
-The bios is up to date along side with windows 10 and all drivers
-It only happens when the laptop is plugged in to power and set to " Balanced " or " High performance " in battery settings
-It happens so often lately but not all the time, when it doesn't (even while gaming) the fan spins normally and does a pretty good job at cooling
-According to HWMonitor, the thermals are normal when the fan is not noisy (40c on idle/70-80 while heavy gaming)
and the thermals while it's noisy are ALSO NORMAL ( same numbers above )
-While gaming on battery it does not get noisy and the fans are normally spinning
-When the noise starts happening and I unplug the charger the noise keeps going until I shut the pc down or put it to sleep or put it on battery saver mode and wait a minute and then it stops going loud

I am so confused because if it was dust or a broken fan blade it should be noisy all the time
If it was a Windows bug it shouldn't do that in the BIOS screen
The BIOS is up to date and set to default settings and it started happening although I have never updated nor messed with the BIOS.
Thanks for the help!

 

[hang-the-9]

If laptop is in warranty I would contact ASUS. I have seen bugs in systems where they needed a BIOS update to fix fans from getting too loud. The reason they don't get loud on battery is most likely because you are using the default battery settings that step down speeds of the components so they don't get hot enough to spin the fans as fast.

 

[toutougroup96]

If laptop is in warranty I would contact ASUS. I have seen bugs in systems where they needed a BIOS update to fix fans from getting too loud. The reason they don't get loud on battery is most likely because you are using the default battery settings that step down speeds of the components so they don't get hot enough to spin the fans as fast.

sadly I am outside the country I bought the laptop from, and I won't be there for a while.. what else could I do ?

 

[hang-the-9]

If can't contact ASUS then live with the fan noise till you can, or crack it open and replace the fan and re-do the thermal paste with a higher end one.