Hypothetically: Multiple CPU's, one watercooler

[Collective_8472]

Hypothetically speaking, would it be possible to cool three systems:
3 CPU's (2x P4 1x AXP)
2 GPU's (2x GF4 Ti4600)
3 North Bridges (3x KT400 or equivolent)
4-6 sticks of DDR400 RAM
all on one watercooling circuit (pump, blocks, heater core, etc.)
Space for the radiator is limited to 20"x14" (atual cooling surface).
Any ideas?

This is for a project to create a multisystem environment with very low internal airflow, high mobility and coolness factor.

 

[Quetzacoatl]

Highly unlikely, first off, if you ran this through even one system, the water passing through a CPU, GPU, North Bridge, and (ram cooling?) a hard drive would limit your cooling to 20-30 celsius. You throw in the parts for 3 more systems, you're most likely going to only see 30-50 celsius. It all depends on the quality of your water pump and the radiatior. Another factor (sometimes you can't control it), is the size of the tubing between the parts and the radiator.

Instead of Rdram, why not just merge 4 Sdram channels...

 

[Collective_8472]

hard drive? who said aboit W/Cing a hard drive?
the HD's are going to be aircooled in a separate compartment (let me worry about how).
I'm not looking to freeze the CPU's or anything, just make the 3 systems as cool as the could be with a conventional air cooler, though with limited airspace watercooling is the only option available to me. besides, airflow is nearly non existant in an area with 3 mobos and connectors thats only 24" x 20" x 6"

 

[svol]

Hmmm... there are a couple of ways to do this... but I don't think a single radiator will do as your heat output will be very big.
You probably should connect all devives in serie... parallel will need one heck of a pump.
But because the water will heat up much in a serial cooling setup you might need to run it through a radiator after 4 waterblock and then go through the remaining 4 (watercooling for RAM isn't needed and will be hard to find) before going to the last radiator. You still need a pretty strong pump this way, but I think it is reachable as long as the tubes are big enough.

My dual-PSU PC is so powerfull that the neighbourhood dimms when I turn it on

 

[Collective_8472]

space is EXTREMLY limited in this design, a serial design is a nessesity, but this thing has to look good (windowed case). any ideas on tubing size if each system has a radiator with one pump?

 

[svol]

It depends on your waterblocks and radiator... but 10mm inside diamater is often used.

My dual-PSU PC is so powerfull that the neighbourhood dimms when I turn it on

 

[Collective_8472]

i'm in the US, and although i LOVE to think in metric, everyone else here generally does not :-( so the piping i'd be getting is the standard 1/4" type (about 10mm int. dia.)
this is gonna be a nonconventional setup (we don't need no stinkin' ATX boxes) so methinks to maximize efficience hard PVC will be used to go from pump to system (switch to flexible tubing if nessesary between the blocks) and hard PVC returns to the radiator(s).

 

[Schmide]

I would add that unless you have some good airflow somewhere, you are not going to be able to radiate that much heat. Even a huge radiator is just going to become a heat store unless you move enough air through it. In terms of actual area a 4-inch square radiator (10cm) per setup should be fine. That comes out to a total 7in (17cm) square radiator and you have (20in x 14in) 17in (42cm) square, so you should be fine. You may think of using half the 20x14in area for air intake, as 10x14in ~ 12in (30cm) square which is more than enough.

Dichromatic for your viewing plesure...

 

[Collective_8472]

actual dimensions for the box haven't been finalized, but the radiator will not be in the same compartment as the computers, the radiators will occupy a panel with one side (the exhaust side) exterior, with fans directly behind pushing air out, the intake for the air ducts will be lower, possibly on the bottom of the casing itself (with airspace of course).

I'm assuming the hard, opaque type of PVC pipe (don't know the offical designation... yet) of 1/4" internal diameter can be used to connect the radiator and pump and feed the lines to the system compartment (flexible tubing there, to allow for maintenance).

This is one part of a rather complex project with a very unconventional approach. you'll be surprised by the end result if it ever works <g>

and how big of a pump will i need (and resivior for that matter).

 

[kisrobert]

I think with a powerful pump you can connect them serial.
When I turn on my pump (450l/h 120 gal/h), I cannot measure the temp difference between the ingoing and outgoing water (but I cool only the cpu). And this was the smallest pump I could buy...

Your pipes are 1/4" (6,3mm) or 3/8" (9,5mm -> about 10) or 1/2" (12,7mm -> internal diameter about 10)
The 1/4" looks to be small.
For this compact size you'll need a big&fast ventillator on the radiator, and you should care about the air ventillation of mobos. There are some part which will need an extra heatsink.
The 20x14" is a quite big radiator- my car have about the same size )) .
For the tubes: why do you want hard tubes? It will be a portable computer, with shaking, droping, leave in the cold dickey etc. Don't you worry about breaking the tubes? I think flexible pipes would be better...

 

[scalar]

The main issue here is what's called <b>heat capacity</b>. If the water is fed serial from system to system, you can't have the water moving so slow that it is already very hot after the second system. It has to move with enough velocity that it can still pull heat off the last machine.

If you stay with the usual quarter-inch tubing, the water may need to move with a fairly high velocity to still be able to cool the last machine. Small tubes cause a lot of resistance to flow, so you may need fairly high pressure.

And so here's a <b>warning</b>.. do you think any of the water cooling kits out there care about pressure testing their systems? Heck no, because at most they run at about 1-2 psi, with low-flow resistance. It is very possible for your cheap plastic hoses to fail, or for the water cooler plate to blow apart, or for your press-on hose connections to blow off.

This will be interesting. Go get yourself a nice 1/2" water garden pump, which can shoot water about 4 feet into the air, or hell if that doesn't seem good enough, get yourself a nice 1-inch 1/3rd-horsepower jet-pump for shallow wells. (You can find these at a house-construction store.) These puppies are designed to move 10 gallons a minute at approximately 20psi, and with flow resistance can develop anywhere from 40 to 110psi. Erm, okay maybe that's more than you need..

Make sure you use hose clamps, because if a hose blows off you'll have a very big mess, possibly smoke and big sparks too as the water shorts everything out. Make sure your hose clamps don't touch anything and short out something.

And oh yeah, I am not an expert and I don't recommend trying any of this, so don't blame me if the computer is trashed, the floor is warped from water damage, or you accidently burn the house down. Have a nice day.

<P ID="edit"><FONT SIZE=-1><EM>Edited by scalar on 01/15/03 04:48 PM.</EM></FONT></P>

 

[scalar]

If you got the cash, here's a company that will be happy to engineer a nice compact radiator that will dissipate the heat from all three machines. Though you may need to know the amount of heat in BTUs you are trying to dissipate, but they could likely over-engineer something that would do the job just as well..

Personally, I would suggest nice compact unit, say 10 inches tall, 10 inches wide, and oh 18 inches deep, with a nice 10-inch axial fan blowing air through the coil. Might need a supplemental fan on the backside to "pull" the air through.

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[scalar]

Actually a nice "safe and simple" design is to just use three separate pump and radiator kits. Each board gets its own radiator.

Cooling will be a problem though if you want to "stack" the radiators in line so they fit in a small space. This can be done, but you would have to invest in some unusually high velocity fans to force the air through all three radiators.

The usual little fans used on a single radiator likely won't have the power to push the air through all three, at a speed high enough to keep the last one in the line from overheating. I suppose you MIGHT get the little fans to work if you made a stack of fans and radiators..

ASCII-art drawing..
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|fan || radiator ||fan || radiator ||fan || radiator ||fan |
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'----'| | | | | |'----'| | | | | |'----'| | | | | |'----'
'-+ +-------+ +-' '-+ +-------+ +-' '-+ +-------+ +-'
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motherboard-1 motherboard-2 motherboard-3
</pre><p>

 

[Collective_8472]

i think i need to clarify a few things here, though there's a good amount of discussion here

the whole rig will be enclosed in a (as of now) rectangular box measuring:
28" Wide
39" Long
17" High

the radiators will occupy one of the widthwise walls of the box, lined up along said wall, not stacked. air intake for the radiators will be supplied by holes in the sides of the compartment on the left and right with the hot air blowing out the front. in a separate compartment, the motherboards are mounted flat (desktop case style), with the hard drives in the same area (HDD cooling fans provide airflow to cool RAM and other nessesites) PSU's are located underneath the mobos.

Confused yet?

once i draw up plans i'll show em around, it seems to me 1/2" tubing is a nessesity...

 

[kisrobert]

About heat capacity in numbers:
specific heat of water:4185 J/(Kg*C)
density of water: 1000 kg/m3 -> 1 kg/liter
heating capacity: 500W (J/s) (3CPU+2GPU+overload factor) serial connected
allowed changement of temperature: 1C
____________________________________________
You will need
500 [J/s] / 4185 [J/(Kg*C)] / 1 [C]=0.12 kg/s = 430 kg/h --> 430 l/h
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if the internal diameter of your pipe is 8 mm then the velocity of the water is: 220 cm/s -> 2.2m/s
------------------------
so if your pump really able to pump 450 l/h then the temp. difference (between the water go into the 1st CPU and the water come out from the last CPU) will be less then 1C.

 

[LCARS]

I'd consider placing the components so the heat will flow away from them naturally.

Like put the PSUs above the mobo and have the air blow out the top of the box (or top-back/top-front).

It sounds like what you need in terms of a radiator is an actual car radiator from a Honda or something. I noticed that the radiator out of a '91-'97 <A HREF="http://www.jeepradiator.com/radiators.cfm?carmodel=cherokee" target="_new">Jeep Cherokee</A> is 31" Long, 11" Tall and 1 1/2" Wide and has a filler tube with cap.

As for pump, I'd go with the Eheim 1060 pump- it'll do 600 gallons an hour (or 2280 l/h).

 

[knowan]

You also have to consider the entire hight of the system. Take the distance between the highest and lowest point in the system. Ideally it should be less than a foot. As you start getting higher and higher you start needing a bigger and bigger pump. That calculation of 450 lph (roughly 120 gph) is for a perfect system and doesn't take into consideration resistance from the tubing, height differences, imperfect heat exchange between the radiator and the air, etc. Ideally the water should be traveling at a minimum of 450 lph when it exits the last radiator. Dangerden did a test and found that the Enhiem 1250 (a high quality 350 gph/1200 lph pump) was pumping the water at 120 gph (about 455 lph) after traveling through just one radiator core. <A HREF="http://www.dangerden.com/articles/flow_test.htm" target="_new">http://www.dangerden.com/articles/flow_test.htm</A>.

A good rule of thumb is that to efficiently watercool one computer given a maximum traveling distance of one foot, a 200 gph pump is about right. Since your doing 3 a 600 gph pump would just fine.

The Eheim 1060 is a wise choice. It is quiet, reliable, and pumps 600 gph. I would recommend 3 rads from a car heater coil. They have been proven to be most efficient. Unfortunately I din't know if all 3 will fit in your setup.

The wateblocks et all should be able to handle the pressure. Dangerden rates their blocks up to 1000 PSI, check out <A HREF="http://www.dangerden.com/base_pages/articles.htm" target="_new">http://www.dangerden.com/base_pages/articles.htm</A>. They also make their waterblocks with both 3/8 and 1/2 fittings, I would recommend the larger 1/2. Just make sure you clamp the hoses. I would also recommend a large resevoir since heat exchange can occur in the resevoir as well, especially if it is made of metal.

Finally, you haven't actually explained what kind of room these will be in. Don't forget that a radiator's purpose is to transfer the heat from the water to the air. As the air heats up so will the water. If you put the whole thing inside a box that box will heat up very quickly. If the rads vent into a bedroom sized area you should be alright.

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