bequiet 500dx silentwings 2 getting louder idk why

[Luukski]

not a month ago i've got a new pc.

but the fan noise is getting louder than it was

im using the bequiet dark Pure base 500dx and the Bequiet pure loop 240mm

all my fans are silentwings 2.

the radiator is on top with 2 exhausts, 1 rear exhaust and 2 front intake. (i know negative airflow)
im using an msi motherboard and im using the silent function at the fan controller in dragon center.

at the beginning it was after a long session school and gaming it was a bit louder. but when it was off for 30 minutes it was as silent as in the beginning.