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  #1  
Old 06-12-06, 06:27 AM
alex_d alex_d is offline
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cooling 8 CPUs at once (>1000watts)

I am looking to watercool an entire (small) cluster, and so the requirements are pretty monster compared to just a gaming rig.

My question is what the pipe/pump situation is like for this.

Ie, what diameter to choose to get a decent flow rate (1-2 gpm) without too crazy of a pump. What kind of pressures would I need to push that much head?

Problem is that space is a big issue, so i'm looking for the thinnest tubes I can get away with (3/8"? 1/2"?).

Also, I'm planning to use several pumps in series to boost pressure, but I also wish to have failover. Is that possible? I'm guessing that some types of pumps (centrifugal?) would let water flow through them easily when they're broken.

The radiator, too, is gonna be a . Any rules of thumb for radiator size, fan size, fan speed, etc? The radiator can't get too huge, and the number of (quiet!!) fans I can fit is also an issue. I did a quick calculation and to cool 1kW you need to heat 250 CFM of air by 10C. That scares me a little.

The biggest criterion is size, followed by reliability and noise. Cost... not so much.

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  #2  
Old 06-12-06, 06:40 AM
markkleb markkleb is offline
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I would build a big CrossFlow design with a small car rad.
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  #3  
Old 06-12-06, 07:32 AM
Nagaru Nagaru is offline
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I would use an Iwaki MD30 or the RD20 they should be more than enough pump. I am not sure if they will allow water to flow through, but I don't see why not. The other thing I would consider is the restriction of the water block vs its performance. A low restriction block should be good, aka no Storms. You will want bigger tubing for good flow, although 7/16" would be better than due 1/2" due to less turbulence at the barbs. Although I have never done something like this I would go with a more parallel system with one radiator and 2 or three loops, this should help to keep the temps down.
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  #4  
Old 06-12-06, 04:04 PM
ai_01 ai_01 is offline
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dual PA 120.3 Thermochills, apogees for cpu block or TDX for lower pressure, two DDC+ with Petras top. could do two loops or just one massive one, id get a pretty big res too.
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  #5  
Old 06-12-06, 11:42 PM
alex_d alex_d is offline
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thanks!

nagaru, the Iwaki pumps look really good. The MD-20RZ or the RD-20 seem perfect (physical size,head,flow,etc). What's the difference between the two? Noise? Cost? Why don't people just buy the smaller RD's? Also, I gotta find out more about how reliable the magnetic drive is... maybe going multi-pump is unnecessary.

As for having multiple loops... I was thinking about that... but I obviously can't have an individual pump for each loop (just more unreliable) and I can't figure out if simply forking the loop will get the right flow to the right places (even if the loops are symmetric). It should... unless some heatsink has a defect or some pipe has a kink and it comes back to bite me in the ass.

ai_01, do you really think two thermochills will do it? Are you talking about super-powerful 120mm fans or quieter ones? Also, how big is a big reservoir? Will something like 1-2 liters (half a gallon) last for 6 months? are there special tubes I can buy which don't evaporate as much water?

also, whats crossflow?
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  #6  
Old 07-12-06, 12:04 AM
NoL NoL is offline
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MD to RD I beleive is also the heatdump and I beleive there actual statistics are different.

Water does not evaporate in our closed loops, you dont actually need to refill them for them to operate, a res is a pretty oo aaa thing really while a T-line is all thats needed.

As for radiators, if your aiming for low noise while cooling a large mass, large volume is required. This would require a much much bigger rad than I think your willing to take on and I would personally suggest 3x bip3 all with yate loons. For pumps, the iwaki is ideal, as for blocks, apogee is probably your best low restriction bet. 1/2" tubing is more then enough as well as the fact that head really only means how high the water will be pushed at max with ZERO flow. So if your thinking about multiple setups next to each other, water picks up what it lost when it falls

What are you actually cooling? (how many and of what type)
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  #7  
Old 07-12-06, 12:04 AM
Nagaru Nagaru is offline
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I believe that the RD is 24VDC whereas the MD is AC.

On the multiple loops, I see what you mean and I can't think of a reliable way to ensure even flow either.

Also what kind of performance are you looking for?
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  #8  
Old 07-12-06, 12:38 AM
NoL NoL is offline
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Equal flow is hard, but equal restriction can be given a shot.
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  #9  
Old 07-12-06, 12:39 AM
NickS NickS is offline
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OK here ya go man.

So I can't imagine you'd want to spend a crap load on blocks, but this should work well. 8x AquaXtreme MP-05 Pro. 2x MD-20RZ, tons of masterkleer 7/16" ID (smaller than 1/2" but fits over 1/2" barbs, same OD as most 3/8". As for radiators, I'd go with two or three Thermochill PA120.3's or five Swiftech MCR-320's, both with 3x Yate Loons each.

Reservoir? Idk, just an MCRes. That should work well.

Thats if you want them all in the same loop. if not..

MCR120 or Black Ice Pro with a Yate loon or two on it, some cheap pump and a MP-05 Pro.
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  #10  
Old 07-12-06, 01:02 AM
Nagaru Nagaru is offline
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I need to apoligize I put 5/8" hosing in my first post, it was late and I was being dumb. I meant 7/16", I will now edit my first post.
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