A few days ago, I cut off the 8cm psu fan (38cfm@ 32dB) and replaced it with a Arctic cooling fan pro TC (12.1-31.5 cfm @10-23dB rated <-- not sure it can be that quiet at max speed). My pc has been up and running since then, the fan speed is only around 1900-2000rpm which is very quiet (i believe the noise its making is less than 23dB since its quieter than the 24.4dB cooler master fan) and im very happy with the result
Thank you all for your helps escpecially EMPIRE for his suggestion of changing the fan instead of the PSU.