Quote Originally Posted by DeathWalking View Post
Oh my god, please tell me Gauss' Law does not apply to fluid dynamics!
Gauss, it was Gauss!! If I don't remember it wrong this is what our physics teacher told us, that the same rules apply for liquids and current, and so we use the same law (Gauss' one).

Quote Originally Posted by Martinm210 View Post
We only need some pressure to keep our tubes formed, otherwise what we really need is "Pressure Difference". That's what pumps give us, a pressure difference from the outlet back to the inlet, and it's this pressure difference that's the form of energy that moves the fluid around. That's all it is, the pump produces the pressure differential, then the blocks and rest of the system absorb that pressure energy as the fluid moves around the system. Pressure difference is the only thing (Besides gravity) that can move a fluid.

Even in an open loop system, the pump is still just producing a pressure difference, but there is a distinct difference. In an open loop you can gain or loose static pressure energy. If you pump water up 100' into a tank, it now has alot of stored energy in the form of elevation. In a closed loop, any water that is pumped up, comes back down so static pressure gains and losses net 0. All we're left with is pressure drop (difference across blocks, etc due to friction), and pressure gain (difference across the pump). Both of these have a performance curve. We just refer to the blocks/fittings as pressure drop. And it's also more common to "Think" of pump as pressure head. But in the end what's really going on is pressure differences, the actual pressure numbers themselves are not important, only the difference.
Thx Martin for your time, I still remember the very first time I came across your reviews and i was like "No way, those graphs have to mean something but yet I've got no clue about what the hell they do mean". Now everything seems a bit more simpler...thanks to you and other people who invested their precious time trying to show the others how do thinks really work.

Ok. So pressure is used in order to make the water "move" around the loop. If we get it to 0, then there is no flow, in some ways it's like friction because it opposes to the movement...yet it depends on it to be there (as there is no friction is there is nothing trying to move).

OK, to sum up and to check if i've got everything alright (if I haven't I'm gonna commit suicide, i swear
So, when you choose a pump, the only think that really matters is the flow rate...and the pressure if you would exceed it, otherwise it just doesn't matter at all. The shortest the circuit the better because you reduce pressure drop (as everything in the circuit reduces pressure). And, the other doesn't matter at all cause the flow is constant throughout the loop (BTW, you said that rad after pump is a good idea because doing so the cpu block will get the very coldest water... but now that I think about it, the difference might be totally negligible as the pump would only put about 20W in the water, which is nothing compared to all the other heat other blocks put in...).
Mmmm which means that a D5 is the way to go if you aren't going to put many blocks or they aren't really restrictive and the DDC is better if you are putting plenty of blocks or a hell of a restrictive one. BTW, is there any way to mount a loop (a possible one, not one with 10 blocks) with a D5 in a way that the total pressure drop exceeds the head pressure and so water just doesn't flow? Because if there isn't (or at least not one that you will ever do) I don't see the point about not buying the D5...

You'll find that most of the highly debated topics are generally those that are either hard to measure, nobody has tested them, or they are generally insignificant. I didn't believe it much myself until I install a thermal probe before and after my CPU block. I got bored looking at the same insignificant difference. Temp out was always just a couple of tenths of a degree higher than in...not very interesting.
But that's something that doesn't need rocket science to understand (if you compare it to all the other stuff) If you just take in account how much water flows at that point it's pretty clear that you will need a hell of a good instrument to measure the difference between inlet-outlet temperature.
I guess it's the only part I could understand precisely (not much, but hey, its a start).