I was just looking at some pumps and got to thinking, In a car, if the water gets pumped through the radiator too fast, the water doesn't get a chance to get cooled off enough. That same thinking should apply to computer watercooling setups. If your pump pumps the water too fast through your system the same thing can occur. I wonder what the gph limit for effectiveness is? My little 4 pass radiator would probably get overrun pretty easily.