[Skulemate]

fhorst, your last post is quite hard to follow. However, I will try to offer some help if I can. As Althornin alluded to, the pressure drop encountered with a system is directly related to the flow rate achieved, and is generally a function of the flow rate squared. And he is correct when he states that there will be a very small rise in the coolant temperature after cooling a CPU, given a typical flow rate and heat load.

I think that you may be confused by the relationships between flow, pressure and the fluid's velocity. All of the blocks you have mentioned work mainly because of a jet impingement effect that is the result of carefully placed jets that serve to increase the water velocity, aiming it toward the area directly above the die of the CPU. Note that it is the increased fluid velocity that is key here, not the pressure, or even the (system) flow rate. In each of these blocks the increased velocity was achieved by decreasing the diameter of the nozzle (or nozzles in the case of the Cascade)... this serves to increase the water's velocity for a given flow rate, but there is a cost involved, and that is the high head loss associated with such a restriction.

This is indeed where pressure comes in, as the pressure gradient caused by the pump is the driving force causing flow within the system. Note that I said pressure gradient and not simply pressure... the actual pressure within the system (or the block) probably doesn't matter a whole lot in terms of cooling (i.e. you could pressurize the entire system if you liked, but there would be little point as the pump would still produce the same flow driving pressure gradient).

Your comments regarding the linear scaling that "would" occur by doubling the rated flow of one's pump shows that you have only a passing understanding of how a pump interacts with a given system. I would recommend that you take some time to read pHaestus' ProCooling Pump Comparison, as there is a very clear illustration that shows this interaction far better than I could explain it here. Keep in mind that there are far more variables that need to be considered besides the maximum (zero head) flow. I hope this helps.