[Beowulf] 96 cores in silent and small enclosure

Lux, Jim (337C) james.p.lux at jpl.nasa.gov
Thu Apr 8 10:01:14 EDT 2010


The challenge with all liquid cooling schemes is leaking and spils.  If you have pumps and tubes, inevitably, something leaks.  If you have a tank of coolant, you wind up taking the equipment out of the tank, and it drips.

The most annoying thing about oil is that it is really good at wicking up the inside of wire by capillary action.  So you either have to arrange for sealed feed throughs or use only bare solid wire where it penetrates the surface.  A remarkably small crack or hole will let the oil through.  There's also the "thermal pumping" problem.  As the oil changes temperature (either from turning the gear on and off, or because of temperature changes of the room) it expands and contracts.  If you have a perfectly sealed (hah) container, that means the pressure of the oil will change, tending to push it into small crevices/cracks/along the gap between insulation and conductor in a wire.  But, if you vent it, then you have to worry about atmospheric air bringing water into the system as it "breathes"  And, if you have a vent, inevitably, the oil will find a way out.

Don't get me wrong....liquid cooling is great.. Oil insulation is great.  It's just a mess and you need to be ready for it.


On 4/8/10 6:38 AM, "Kevin Hunter" <hunteke at earlham.edu> wrote:

At 12:57am -0400 Thu, 08 Apr 2010, Jonathan Aquilina wrote:
> i know there is non conductive water which if it gets on
> something shouldnt conduct electricity but how safe is a
> water cooled system?


How safe is it?  I can't answer empirically (no experience), but in
theory it's just as safe as air.  Water is never in contact with any
electrically charged object, and never leaves it's tubing channels.

Kevin


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