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.

I would build a big CrossFlow design with a small car rad.

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.

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.

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?

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)

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?

Equal flow is hard, but equal restriction can be given a shot.

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.

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.

Nicks you chose some of the highest restriction blocks, why?

man, i'm really impressed by the amount of stats some manufacturers have on their websites. Everyone's got pressure-to-flow graphs for their pumps (not just meaningless max head, max flow), but swiftech's even got a ton of data on stuff like radiators.

Looking at their figures for the MCR-220, it seems that with a 20C air-to-coolant temp delta (i'll get to that in a sec), it can dissipate 500 watts at 30 dbA. So maybe I can just get away with two of those (or at least maybe if I use a better 2-fan radiator and better fans). It almost seems tooo easy...

Anyway, NoL is right and I have to explain exactly what I'm doing. I am looking to cool 9 Kentsfields in a blade configuration (ie, really close b/w the mobos). There'll be no overclocking, and the chips are no whimps about getting warm. Also, we pay the AC bill. So I think a 20C delta (25C air + 20C air-to-water + 10C losses at the waterblock, et c.) still puts me within spec. Needing just two 2-fanner radiators would be really good.

The waterblocks have to be not perpendicular-angle. Swiftech's apogee-1U are looking good. There also of course there have to be ZERO LEAKS.

And it's important that $10k of equipment doesn't fry if a pump dies. I've been meaning to ask... are there watchdog devices that'll cut the power if flow/water temp goes out of spec? Better yet, I'd rather not have it crash either, which is why i'm investigating pump arrays. It's kind of frustrating me, though, that pumps seem to be rated for just 50k hours. That's basically saying one of two pumps WILL die over five years. Since the actual maintainers won't be whizzes at water cooling, this point is really hurting my balls. I need more reliablity and I need pump replacements to be brain-dead simple. This could very well be the thing that kills the idea. Is there anything along the lines of special connectors or valves that ease draining, hookups, prevent dumb mistakes, etc.?

NickS, thanks for the tip on the tubing. Are there any drawbacks to thinner-walled tubes? (I know for a fact that at some point water does evaporate through plastic)

you guys wait and i'll post a cad drawing of what I hope the beast will look like

@ Nol Because A. They're good, B. Dual Iwaki's will be fine .

I just don't like Apogees. Dunno why but I don't like swiftech blocks in general, cept the 6000/6002 series.

Swiftech isn't the good company everyone sees. I know you know this but I dunno if everyone else knows, Swiftech didn't even design the storm.

Neither did Swiftech design almost any of its blocks Nicks, they're quite the buy-and-mass-produce type. 6002 was great, but I figured he would be saying 1U range.

The 1U Apogee will cover all your needs, but 9 kents... Thats definitly going to be alot of heat to remove. I'd say more of a 1500watt range actually. Since this seems to be a simple keep the temps under control sort of thing, I think dual MD20 bored out to a larger ID, using 3/4" tubing then split down to 3/8" to go from 1 3/4" tube to 3 3/8" tube would be your best bet. Your not actually after killer flow, just flow itself.

As for radiators? Possibly a MCR220 after each line of 3 Kents?

Motherboard will also cut the power when it hits a thermal point.

Yeah that'd be a very budget-concious idea. MCR320's are about $50, I'd go with four though. Nine kents plus the small but large heatdump of the Iwaki's? They use 50w but they don't dump that. Prolly around 25-35w dump.

Anyway, I wanna see a pic of this after its done .

@ NoL, 1U apogees? If these are going to be in cases, that'd be kind of hard since they use 90* barbs. :\ Regular apogees would be good since they're not as restrictive.

NickS said:

Yeah that'd be a very budget-concious idea. MCR320's are about $50, I'd go with four though. Nine kents plus the small but large heatdump of the Iwaki's? They use 50w but they don't dump that. Prolly around 25-35w dump.

Anyway, I wanna see a pic of this after its done .

@ NoL, 1U apogees? If these are going to be in cases, that'd be kind of hard since they use 90* barbs. :\ Regular apogees would be good since they're not as restrictive.

Click to expand...

You really need to pay attention...

name='alex_d' said:

The waterblocks have to be not perpendicular-angle.

Click to expand...

Also if you WERE to go for a res dont bother with that tiny little MCRes, get some sort of large finned tank. Either way i wouldnt bother with a res, just get a bigger rad. Water cooling can only go as low as room temp remember, so the longer the water has in contact with the air the better the cooling will be (im not suggesting you expose the water though lol)

alex_d said:

And it's important that $10k of equipment doesn't fry if a pump dies. I've been meaning to ask... are there watchdog devices that'll cut the power if flow/water temp goes out of spec?

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yes i think there are systems that do this but they wouldnt take the kind of flow you want and if they do theyre quite restrictive. It would be fairly easy to make one of these and if you live within mailing distance i wouldnt mind having a shot at making you one, just need to know the diameter of the tubing you decide on

Oh, I finally understood the point of forking into multiple loops... you make a tradeoff of halfing the pressure but doubling the flow... a good choice if your pump's designed for that (and most are). As for uneven flow... after studying the graphs of pressure-drop-to-flow of the apogees, it seems that if one loop starts to go much faster than the other, the pressure drop will quickly rise balancing things out (like... a four-fold pressure difference translates into a two-fold flow difference which translates into a maybe 30% cooling difference). I.e., I shouldn't worry about minor kinks, defects, or different tube lengths.

That really changes the picture, and a low-pressure, high-flow system may be better than a single high-pressure, low-flow loop... but that's what NoL and others were saying and I guess I should be listening better.

I'm trying to do some rough calculations. Just to figure out the pressure-flow situation. I was going to ask you guys about the pressure drop of tubing, but found this site first:

http://www.engineeringtoolbox.com/pressure-loss-plastic-pipes-d_404.html

Seems that with my target 1 gpm of flow, even 3/8 tubing will lose just 4.3 feet of head over 100 feet of tube. Sounds pretty good to me (and i'm eyeing the masterkleer anyway).

ok... a couple questions... what's a good place to find/research various connectors/valves/etc (for that easy pump changing I was talking about)? And are there any other pump manufacturers i should be looking at besides Iwaki and swiftech?

P.S. for those with experience... would anything bad happen if I fork into 9 symmetric loops instead of 3? It'd make the hookup much easier.

er http://www.engineeringtoolbox.com/pressure-loss-plastic-pipes-d_404.html