Well, the thing is with these water cooled systems is that we are often using pumps from aquarium outfitters or comparable pumps made by the same companies. I actually use those eheim pumps for my fish tank, But i just wanted to say that usually when i buy a pump i will look at the gallons per hour or gph, that is kindof self explanitory, it will tell you on average how much water will flow through the pump during a period of time. This is very important to read when you purchase the right pump. Also it will show how the power is significantly decreased if you have a sump type of cooling system and the pump pumping water up to the pc. These are just a few things you should look for while shoppin for a pump