Uh... yeah, right.
Ok, so that everybody is still clear...:shrug:
There is an overall pressure, that affects all the components simultaneously. It is similar to atmospheric pressure.
There are also individual pressure points, where for example, the pressure is high inside of a waterblock, because there is a lot of flow resistance. This pressure is due to the speed of the coolant, and not the flow rate.
Ex. If you try to cram 1'000 gph through a 1 foot pipe, there will be a lot of pressure on the walls of that pipe. On the other hand, if you try to run the same 1'000 gph through a 24 foot pipe, the pressure will be minimal, and the 24' pipe can handle the little pressure very easily. SAME flow rate, different speeds, different pressures.
These individual pressure points exist regardless of the atmospheric pressure.
The res may induce an overall pressure.