[MaxxxRacer]

I did look up the compressibility of water and I'm sorry for saying that it isnt compressible. From my research I found that it is actually compressible by 1%. Not much, but its still something. Apparently this happens in insanely powerful pumps like for dams and stuff..

I realize that the pressures are relative. I stated that. I didnt directly say relative but its implied in the text.

Let me explain this again. If you had the block after the res, the pumps head pressure would NOT be pumping water through the block. in actualitity the vaccum created by water flowing through the pump would in effect drag water through the water block.

If there is any component after the res and before the pump this component will cause cavitation in the pump (given that the component is restrictive) becuase the pump will be starved of water. this is so becuse the pump is having to suck water into itself from the res. it is just taking the water from the res. the water in the res isnt be forced into the block. its being pulled in.

So this proves that order does in fact matter. granted this wasnt exactly my origional point (origional point regarded the block and the rad). Here is a simple way for you to test my pont. See the tube leading into your pump. sqeeze down on it a bit and see what happens. it will fuxor the pump. By that i mean that you will start to hear cavitation and then see bubbles running through a close loop. if you squeeze down on the tube leading out of hte pump you will see that the pump will do fine. nthign willl happen except for slowing down flow due to restriction.

When you said that having the block after the res in your example would give a psi of -3. Well in a way you are correct. the pressure causing the flow throuh the block would infact be coming from after the block. and not before it. This pressure being negative pressure. With negative pressure you get suction. this suction would pull the water through the water block. Here is some testable evidence to the negative pressure.

Why is htere cavitation in pumps. Becuae the pump is not getting enough water and it is pumping so much water out of the pump that there is a negative pressure build up inside the pump. when you have negative presure in water it starts to release bubbles (cavitation). The reason is because when you decrese the pressure of a liquid in decreases the boiling temperature and in effect you are boiling the water at room tempeature. cool sh!t huh. a little chemistry there for you. its cool stuff. but anyway.

The above example proves that the absolute numbers are actually important and not just something that can be disregarded.

Myself i dont have much tubing to spare and really hate messing with my system. But if you want to try putting your cpu block after your res. see what happens. I GARUNTEE you that you will get worse performance with the block.

As you mentioned the water being denser where the psi is higher isnt the issue. what is the issue is that with modern blocks, they dont rely on flow so much as they rely on jetting the water into the block. with higher psi behind the block then there will be stronger jets. if the water is being pushed lazily through the block then there wont be the jetting effect and thus the blocks true performance is not realized.

The reason that you think that it is entirely about flow is that to obtain these higher pressures that give you this "jetting" effect inevitably have to be higher flow.

now for the old dnager den blocks for the gpu and the zchip NB block. those blocks rely entirely on flow and are relatively un restrictive. The maze4 is also one of these blocks that relys entirely on flow and not the "jetting" effect that i was talking about.

the jetting effect is present in the WW, Cascade, TDX, RBX, Storm, Radiical WHX, X4PRO X3M, Asetek Antarctica, and others that i dotn know exist.