Not sure if it helps but I moved from stock corsair H80 fans (cooler is probably on a par with the 920 for price and performance) to Akasa Viper fans in push pull, very happy with the end result, temps are still nice and cool, but doesn't sound like a jet fighter on full load.
Other suggestions for rad fan's I hear allot of is the 1850rpm gentle typhoons, a great deal of suggestions for these.