The stock fan on the Corsair H55 Liquid Cooling kit runs at 100% all the time which is about 1600-1700 rpm! So it's pretty loud and I don't have the money to buy new fans.
I run 2 fans on my H50, the main one is connected to the CPU fan head and the second one has a 3 speed switch on it.
How are you hooked up?
Just above my CPU socket on my motherboard is two 4 pin CPU fan connectors, the fan is in the main one and the pump is in the optional one. However, the fan is a 3 pin fan.
I just looked at mine. I hooked the pump power to the CPU fan jumper and the radiator fan to a system fan jumper. I have a second fan on mine as well, it is hooked to another case fan jumper on my MoBo, it has a 3 position speed switch, I leave it in the middle.