[Beowulf] /. Cooler room or cooler servers?

[Mark Hahn]

> Water has all sorts of nifty properties -- large heat capacity (relative
> to air), intermediate boiling point, LARGE latent heat of vaporization

water cooling is certainly very attractive to an HPC installation - 
even if you're not doing high-density stuff (say, >15 KW/rack),
you've still got obscene amounts of space taken up by airflow 
and chillers.

on the other hand, I really don't want 800 water-filled pipes in my 
machineroom.  putting a heat-exchanger on the front and/or back of each
rack would work (SGI does it, as well as some OTC products.)  I don't
think much of the APC sealed-cooled-rack approach, at least not in 
a machineroom, in part because they don't seem to understand that 
machines are front-to-back.  Liebert's top-of-rack boosters seem very
much like a retro-fit solution, to me.

is it possible to make a flexible heatpipe?  if there was a sealed 
heatpipe that sucked heat off my CPUs, that would make the problem 
much easier.  perhaps the cold end of such heatpipes could be cooled
by a chilled-water loop (even eth-gly), which wouldn't be as bad
if it had fewer, simpler or factory-configured connectors.

there might be temp-control issues with this approach.