[Beowulf] watercooling

Lux, Jim (337C) james.p.lux at jpl.nasa.gov
Wed Dec 28 11:17:11 PST 2011

On 12/28/11 11:00 AM, "Vincent Diepeveen" <diep at xs4all.nl> wrote:

>Yeah Jim good comments,
>I was thinking for my cluster to overclock, which is why i guess some
>posted the overclocking sentences,
>and wanted to do it a bit more cheapskate.
>Latest idea now was to save costs by using for say a node or 16,
>to order 16 cpu blocks and 16 small pumps and 2 cheap big reservoirs:
>Coldreservoir ==> 16 minipumps ==> 16 cpu blocks ==> Hotreservoir

Hmm.. Over the past few years I've been trying different schemes to keep a
bunch (a cluster?) of glass bottles full of 750ml of an 12-15% alcohol
solution in water at a reasonable temperature (15C or thereabouts), and
I've gone through a wide variety of improvised schemes.  (aside from
buying a purpose built refrigerator.. Where's the fun in that?)

Unless you need small size with high power density, very quiet operation,
or sealed cases, BY FAR the easiest way is a conventional air conditioner
blowing cold air through the system.

Schemes with pumps and radiators and heat exchangers of one kind or
another have maintenance and unexpected problems (stuff grows in almost
any liquid, metals corrode, pumps fail, plastics degrade).

A very inexpensive window airconditioner (US$99, 8000 BTU/hr = 2400 Watts)
draws about 500-800 Watts (depending on mfr etc). The Coefficient of
Performance (COP) of these things is terrible, but still, you ARE pumping
more heat out than electricity you're putting in.

A "split system" would put the noisy part outside and the cold part inside.

The other strategy... Get a surplus laboratory chiller.  Put THAT outside
and run your insulated cold water tubes down to a radiator/heat exchanger
in your computer box.  At least the lab chiller already has the pumps and
packaging put together.  Run a suitable mix of commercial antifreeze and
water (which will include various corrosion inhibitors, etc.)

But really, cold air cooling is by far and away the easiest, most trouble
free way to do things, unless it just won't work for some other reason.


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