[BGP Spook]

If I may suggest it, I try to separate every couple of sentences with white space as it helps legibility. 250 word paragraphs with next to no white space give me a head ache.

Originally Posted by Tachyon

[to shake things up - in reverse order this time]

I have no parts at all that lock me into any design at this point. Just this design that I've become "engineeringly" comfortable with. It's all in my head ... (that's what she keeps telling me as well)

Are you an engineer?

I tend to think you aren't based on some of your descriptions(no offense intended)
but I want to ask anyway. You could be an electrical engineer trying to describe a dynamic mechanical problem in terms you understand.

Regardless, I would call what you describe above being "mentally comfortable" with an idea or method. You have sat down and thought about this for lengths of time and are satisfied that you have covered all or nearly all the angles.

Originally Posted by Tachyon

when is pump head not a pump head?
Consider this, an electric motors sits on a table next to a 10' piece of linear rear.

This linear gear poses no load on the motor while sitting next to it.

Now the motor starts to press this linear gear straight up, every inch adding to a load presented to the motor from the weight of the linear gear it's pushed vertical.

Eventually the motor will stall due to the inability to "lift" any more gear weight. (say 10' of linear gear)

It took me a second read to visualize what you were trying to illustrate.

I understand what you are implying.

I think your example may be flawed, the motor would stall initially rather than once it got to a certain height.

The force of the mass of the linear gear acting on the motor wouldn't change just because it was elevated a short distance.

The acceleration of gravity is constant for small changes in height.

It would, however, change slightly from the acceleration cause by the motor although the change would be negligible for our purposes.

Originally Posted by Tachyon

Now ... lets take this 10' section of linear gear, wrap it around a wheel and place the motor on it.

The will still have deal with inertia [or the lack there of] but it will not stall.

Given a few seconds or minutes it would reach the motors spin rate minus some amount due to friction.

In a water scenario a pump head measurement it taken with a "linear gear".

A open ended tube with which the pump will see how much fluid it can push vertical.

At some point the pump will no longer be able lift any additional fluid weight.

In a closed loop, it'd be taking advantage of the returning fluid’s weight to counter act what would be the "head" or pressure side of this picture.

The pump will take a bit to get the water "spinning" in our loop but eventually it will spin at the pump's rate minus some flow resistance.

All “my” theory but to you follow my logic?

I understand you theory but I am sure not all of your assumptions hold out.

In truth I don't fully understand all the vagaries of fluid Dynamics.

For the pumps you are talking about using I think you may be disappointed.

That is my real concern, that your pumps will be insufficient.

I would add that you are neglecting the effect of friction which one can generally do in mental exercises as long as they are factored in later.

Most people who want reasonable flow rates put one or two of the pumps you would be using on a single loop that only operates inside their computer with about 6'-8' of tubing and one or two blocks.

Having one pump per loop may not be enough if each of those pumps have to move the water 25'. (10' up +10' down+5' for routing)

There are ways of limiting this, example: have both rezes on the same upper floor, but the pumps will still be pushing water through more feet of tubing than the really needed to be.

Originally Posted by Tachyon

...but if you leave your computer on....
that was the one unknown in my thinking. How fast I could heat the basement? I've kept the idea alive for now because of how well this technology has worked. Albeit on a much larger scale than my basement.

The scale is what I am think will limit it, but maybe not.

Do some googleing and research it. Should always be the first step in a project.

If you look around hard enough I am certain you can find a "do it yourself" guide or an explanation on how it works.

Here is a source I found by googleing 'ground cooling.'

Originally Posted by Tachyon

...handicap a loop(s) by under sizing any portion of the tubing...
hmmm I'm not really "reducing" the tubing size as much as I'm giving the pumps unrestricted access to supply. It’s a 3/8” cooling system. I just have 1/2” supply lines to the pumps. Why 3/8”? In my design I have 3 pumps & 3 loops worth of volume.

I didn’t want to have to think about 1 1/2” lines from the warm rez -> radiator -> cool rez. (1/2” times 3 = 1.5” total volume)

With this thinking you are artificially limiting your performance.

Have you ever used a syringe?

It takes a lot of force to expel the contents of a syringe quickly.

If you took the same syringe and cut the part where it necks down off and tried to expel the same contents of the syringe quickly it would be very easy by comparison.

My point is, you will be limiting the performance of your pumps by sizing down the tubing on the output side of your pumps.

The only reasoning you have given for justifying this is that you don't want to use 1.5" tubing between your each rez.

You could use three 1/2" tubes you know and most WCing radiators come in 1/2" or 3/8" sizes anyway.

Furthermore, running radiators in parallel water flow should net slightly more efficient performance, provided that the flow through each rad is sufficiently turbulent.

A couple of threads with links on the subject. Worth reading.
http://forums.procooling.com/vbb/showthread.php?t=12697
http://forums.procooling.com/vbb/showthread.php?t=13792

Please ask questions about the results if you have difficulty understanding them.

Originally Posted by Tachyon

I really dig those Laing pumps. From an engineering stand point they’re nearly perfect. (ok well that input line was a real Homer Simpson) and people here have already shown that a straight in supply with no restrictions (read 1/2 supply line) that these little beggars can really pump it real good .... [wait - write that down I think we have a song here - pump, pump it jam, pump it up.... ] oh yeah.

I guess I am really just questioning your pump choice for what you seem to be talking about doing.

The MCP350 is a very good pump but it has its limitations.

Originally Posted by Tachyon

...NB and SB probably don't need that kind of cooling ...
On the eVGA reference i680 board they've (nVidia) have designed a heat pipe that runs from the SB to the NB and the NB has a fairly good sized fin area *and* it's own fan.

Somebody thought it might be a good idea to cool it better then the plain-ole HS or HSF.

Then again that hardware might just be eye candy or "wow" factor.

As I do not have not gotten any hardware yet... I can't say but this is why I included it on that loop.

It is your money, it is your loop, you already know my opinion.

It is up to you to decide.

Originally Posted by Tachyon

...you didn't understand my suggestion ....
No, I think I did ... I just might be under estimating the ability of water to absorb that much thermal energy.

The specific heat of water is about (4.181 watts * sec)/ ( gram),
with 1 gram = 0.997 ml of water for 25 C ambient, using this table.

Assuming we run a loop in series.

Say 50 ml of water per second (~3 liters a minute) and 100 watts of heat dump.

Where x is the change in the temperature of the water.
100 W =((4.181 J) / (1 g*C)) * ((1 g) / (0.997 ml)) * ((50 ml) / (s)) * x

x=~0.48 C

This represents a fair estimate of the likely difference between the "cool side" and "warm side" of water block of a high heat dump component.

33.3 ml/s =~ 2 liters a minute.

Most systems run closer to 4 - 6 liters a minute, and most water blocks are designed to operate at those flow rates.

400 watts of heat dump is a huge amount, and I consider it a gross overestimate of your likely heat dump.


Where x is the change in the temperature of the water.
400 W =((4.181 J) / (1 g*C)) * ((1 g) / (0.997 ml)) * ((33.3 ml) / (s)) * x

x=~2.86 C

That doesn't mean that the water on the "warm side" of your loop will be ~3C above ambient temperature, that is a whole other set of equations.

What that number means is the difference between the temperature of the water on the "cool side" of the loop vs the "warm side of the loop" will probably be less than 3C, assuming any kind of reasonable flow rate and anything but an insane heat dump.

Originally Posted by Tachyon

You know, I was the only one in high school physics that argued against the theory that warm water freezes quicker then cool water does due to the molecules being more mobile.

I'm looking at it from an over all thermal energy level stand point of view.

You still have to remove "X" amount of thermal energy to get the water to freeze.

But what you're telling me, and please anyone jump in and choose your sides here, is that water is efficient enough at absorbing thermal energy that in our little thermal engines none of the individual parts (CPU, GPUS, Chipset) generate enough thermal wattage to raise the coolant temps appreciably in one, series looped, circuit?

So - someone could take the radiator out of the loop and run the system for a short period of time before the coolant temps rose appreciably.

Correct?

In my current design - guessing and stabbing in the dark, what would you guess the deltaT be between the two rez tanks assuming an average 50% load on the GPU's and CPU? (I realize there are a lot of variables - guess)

See previous calculations.

The temperature difference between the water and the ambient air temperature is very, very much dependent on how you remove heat from the loop.

Such as the number, size, and quality of the radiators you use, and also the air and water flow through them.

Originally Posted by Tachyon

I can certainly grab a hold of the "point of diminishing returns" here.

It's one of the reason's I'm not spec'in this system with a quad-core.

Not much to do for a "double the cost" investment.

What I'm learning here [and exactly why I wanted to engage this forum] is that - sure you can have a triple looped system, but at 2-3 times the cost I'll not see the requisite raise in performance.

Or at least lower temps in any of the individual heat sources.

I hope this is your point and that it has been realized in "real life" experiences.

I do not think I've seen anyone do comparative tests of a single looped system to a system with individual loops for each one of the major heat sources.

I am a little tired and I need to get ready to leave soon but I think I know what you are talking about.

And if so, then yes, that is kind of my aim.

You won't see a linear relationship between your expenditure and your return for what you seem to be planning vs what I have been suggesting.


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And I think this makes it into one of my top ten longest posts on these forums.