Its been years since ive built a custom wc rig but am going to give it another bash so i can cool my 5850 too, question i have is about the pump, ive seen a couple of xspc ones that are bay res ones, i know there probably not the best but of the 2 ive seen one is rated at 750lph and the other at 450lph but both have a head of 1.8m, am i right in thinking the head is the pressure? If thats the case they should be both equal?