This should have the information you need. I believe you get pretty solid cooling at about 30% PWM settings which puts the RPMs on the pump in the neighborhood of 1750-1900. I think there is like only a 1-2C difference at full fan rpms. So 30% PWM on pump vs. 100% PWM on pump with full rpms on fans will net you only 1C difference and it is much louder at higher rpms. Better performance can of course be achieved with push/pull config or adding some gentle typhoons or Noctua NF-F12 fans onto the radiator.