Topic: A journey of extreme watercooling: Cooling a rack of GPU servers without AC. - page 4. (Read 27357 times)

Useless to spent all that time researching, pretty much use any you feel comfortable, or which gives the nicest color in your senses
Forget distilled water, useless waste of money & time for cooling purposes.

Just add at least 1%, but don't exceed 50%.

I'm not a fan of watercooling computers, too much work to maintain and hassle in regular desktops. For servers it makes sense tho.
I recommend the red glycol (i keep forgetting the names lol) because it has the highest boiling point and best protective for modern engines, but for computer watercooling any automotive glycol will work just as fine.

Copper should not be used with Aluminum it causes Galvanic corrosion, don't use Aluminum with anything actually.
I tried EK coolant the first time, I was worried about leaks. About 3 months down the road my cpu block got plugged with little fibers, was a major pain figuring out what caused the flow to drop. I'm not sure if it was the fluid or not. It definitely leaves residue on everything that it touches. Now I use distilled water, along with silver coils and a few drops of dead water. Seems to be working great. Here is a simple guide: http://www.overclock.net/t/913181/water-cooling-guide-for-noobs#post11984918

You know, I spent to much time researching mixtures. One site started that 3/4 Ethealyne-glycol 1/4 distilled h20. Is there a mix you would recommend for effiency ?

Copper + Aluminium in the same loop is not a fatal problem. Those are combined in automotive applications for decades.
Radiators in standard cars used to be copper! Sometimes copper head gasket is used etc.
Newer cars tend to use aluminium cores for radiators due to their lower price and weight.

Just add high quality coolant or in other words: Glycol for protection. The red stuff is highest quality. You need this in any case, unless you want your loop to gather all kinds of dirt, bacteria etc.
It also prevents corrosion.

In this utilization even 1:20 mixture is probably more than sufficient and it's cheap.

Each split has the same resistance because it uses the same components.  That keeps the flow roughly the same though each split.  You couldn't however have 4x5970 in one rig and 3x7970 is another rig.  As long as all the "downstream components" are identical resistance should be roughly the same.  As water velocity increases the back pressure increases and that prevents one loop from flowing faster than another one.

If you did have dissimilar branches you could use a "booster pump" on each branch to boost flows to the one with higher resistance.  As an alternative you could use something called a balancing valve which increases pressure to the lower pressure segment to balance the flows.  I hope to avoid that though (more cost, more complexity).

How do you make sure flow though each of the splits is the same? Or rather, that one or more isn't so slow it causes problems?

I haven't found a good cheap manifold yet.  

The problem is it is aluminum.  copper + aluminum in same loop of circulating water =

If they made that exact item in copper it would be perfect.  

I have been looking for something which is copper with 1" supply and 6 to 10 branches outlets w/ 3/8" or 1/2" npt threads that doesn't cost a fortune.  That doesn't seem to exist.  Lots of radiant heating manifolds but they come with high end pex connectors and cost a fortune.  I may have to break out the torch and make my own.  

You might also consider a bore pump for use in submersible well applications. However that might have a head pressure that is too great.

An update:

Talking w/ some watercooling guys I am deciding on a different pump.



Likely an Iwaki MD series pump.  These are some monster pumps and have a good rep for requirements of large water cooling projects.  Likely I will need a model larger than what most people consider.  I am thinking of the Iwaki WMD-40RLT.

I don't own an RV but this looks like a nice resivour to me

http://www.tank-depot.com/productdetails.aspx?part=85-1859WH



Turn it so the fittings are on top.  
1" in,  1" out, 1/4" vent line, and 1/4" for installing a float sensor.  

I was going to make a cube out of plexi, bond the edges, and tap threads into it but man it is like they made this for extreme watercooling.

Jesus.  This idea is just full of win.
 
It's making my idea to water-cool my 7970 through my aquarium seem like weak sauce. 
 
I haven't done it yet, 'cause it's only 55gal aquarium, and I'm still unsure if the heat exchange in my basement would dissipate that heat fast enough before creating fish-soup. 
 
Should I come across a nice sum of money that my wife doesn't find out about, I think I'm going to steal your idea, DeathAndTaxes.

Impressive job, DandT.  Yeah, get that heat outside.

During the winter I just position my PC next to a slightly open window.  Works great.

better places to put the mining rig:

1. In mountains of Tibet
2. water radiator sunk into a lake, or even better a river

There was a folder on another forum that used a 55 gallon plastic barrel, and a saltwater-rated aquarium pump for longevity. EDIT: Link to forum thread
Do you have your manifolds yet? Here is a good one:


http://www.ebay.com/itm/190550567439

An update (if the updates seem a little rambling they are.  Just trying to get my thought down on paper as I go along).

Heat Exchanger and coolant lines:
So I bought the radiator water to air heat exchanger.  I talked on the phone with supplier, a nice guy who answered all my questions despite me using the HE in a non conventional manner.  It is designed for transferring heat from a wood burning furnace to air handler.





I also picked up some rolls of 3/8" (branch line) and 1" PEX (mainline).  I am still deciding on the pump.  I need a pretty "beefy" pump.  Something which can push 8-12gpm with 10 feet of head.  My first thought was aquarium pump but they are expensive and seemingly under powered.  Next I thought about radiant heating pumps but I would need a stainless steel model and they aren't cheap.  Someone recommended Iwaki water pumps.



Seems interesting.  The smaller ones are used by extreme watercoolers but I need more extreme than extreme.  Nice thing about these is the build quality is second to none.  I would be confident with it running 24/7.  Any thoughts on a pump?

Changes to the plan:
After some thinking I decided to modify my plan a little.  Rather than use a flat plate heat exchanger (water to water) for each rig I am going to run the coolant in one giant loop.  The main reason is cost.  Having a closed loop system in each rig transferring the heat but not water (via heat exchanger) to an outer loop is nice but expensive.  We are talking $200 per rig for internal pump, reservoir, and heat exchanger.  6 rigs = $1200.  Removing that significantly cuts the cost with a little more work when adding and removing a rig.  


So new design will be:
heat exchanger -> 1" PEX -> pump -> 1" PEX -> 8 cold line port manifold -> 3/8" PEX branch lines in parallel -> each of the 6 rigs -> 3/8" PEX branch lines ->  8 port hot line manifold -> back to heat exchanger.

Each rig will connect to the cold and hot side manifolds with no-spill quick disconnects and flexible tubing (likely Tygon).



Bleeding the system will be a little more challenging but $1200 in cost savings makes it worthwhile.  Having a large (say 1 gallon+) reservoir higher than the highest rig.  That should allow water pressure to aid in bleeding.  Possibly 2 reservoirs?

Nobody makes 1 gallon or larger watercooling reservoirs so anyone have any ideas for constructing one? or re-purposing some other gear?   It should have 1" NPT fitting to allow connection to the PEX mainline.

Very nice job, Death!  While I don't have a giant rack for my rigs, it's cool to see that those can be used.  I've not done water cooling before though so yeah while it is tempting for even lower temps, that's a lot of extra parts for even a handful of 5970s. 

That radiator is rad. Same price range as units that are sold for PC's but the advantage of dumping more heat. Schweet!

With PEX you can get a 3/8" inside diameter hose on to a 1/2" diameter PEX fitting (not compression). Fit should be very tight.

That is a quiet option. Even a "normal" radiator is very quiet.  My "test radiator" has 4 low speed 120mm fans.  It is really no more noisy than a power supply (a quiet "woosh" instead of any buzz of whine from high RPM fans).  Even a small amount of airflow can significantly improve the cooling power of a radiator.   4x120mm radiator is insufficient for 4x5970s. 

My goal though it to dump the heat outside thus saving all the AC costs.

I have been contemplating water cooling for my 4RU 19" rack mounted miners as well. Noise is a big issue for me due to the WAF, so I have been looking at passive radiators like these. They take up a lot more room, but are totally silent. My current thought is to mount an array of these to the side of the 19" rack so it doesn't take up additional space.