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sevisehda: Every system is different so to say you should do something 1 way all the time is not productive. Try mocking your system up in a sink with the blocks in parallel then in series.
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Makes sense, though I'll probably use the tub since it has better capacity for flood control
The big question as I see it is that the simulation would lack the thermal input from the processors, so it might be a challenge to figure out how much of an increased total flow volume from running parallel it would take to compensate for the decreased volume going through each individual block.
To save typing;
Op = total output of parallel hookup/time;
Os = Total output of series/time;
Bp = volume through ONE block in parrallel/time;
Bs = volume through either block in series/time;
Now correct me if I'm wrong, but Bs = Os in a single branch system as I understand it.
In a parallel system, Bp = OP/# branches, assuming that all branches have equal flow resistance. I.e. in a two branch system, each block would see 1/2 the total volume pumped in a given time.
Also, within diminishing return limits, the higher the volume flowing through an individual block, the more heat it will remove from the block. However, the hotter the water is entering the block the less heat it will remove per unit of volume.
The issue is mostly a question of in a series setup how much hotter the water going into the second block would be on account of it's trip through the first block, and thus how much hotter the second CPU will run. In addition there is a question of how much the flow would be reduced by having all the water having to pass through both blocks.
The series advocates maintain that the temperature difference between the two blocks would be nominal since each volume of water would only be picking up a little heat in the first block. In addition they feel that making all the water pass through both blocks means that each block will see more volume and be cooled more than the flow would be increased with the lower resistance parallel setup.
The parallel advocates maintain that the greater total flow due to lowered resistance will make up for the fact that each block will only see part of the total.
Now, boundary conditions...
Case 1: Op
< Os - The series folks win clearly, as there is no increase in flow with the parallel setup, and Bp = 1/2 Bs, which would obviously mean less cooling.
Case 2: Op
> 2 x Os - in this case the parallel folks have it easily, since the flow through each block would be the same or better than the series flow, and the increased volume should mean the whole system runs cooler.
I would be suprised to see
EITHER of these cases, but would expect to see something in between, where Op = 1.? x Os. This leads to the main question, how does one estimate the point where one crosses from case 1 to case 2?
I know I've been talking about having an additional low flow branch for the hard drives, etc. I think it is safe to leave that out of the overall calculation since it would be the same in either hookup. (actually it might get LESS flow in the parallel setup since the lowered resistance of the main branches would make the high resistance side branch less 'attractive'...)
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Skulemate: The problem with this is that you do not have the highest flow rate where it counts... namely through the waterblock.
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I don't quite get your point Skulemate, there will be two blocks, and I don't know where else the water would go besides through them (barring leaks
) I am NOT talking about having a 'no cooling bypass loop'! If I split the flow, I would be splitting the cooling loads as well.
Gooserider