[Beowulf] interesting paper re power efficiency

Mark Hahn hahn at mcmaster.ca
Wed Aug 6 13:26:12 PDT 2014


in short, sub-threshold leakage is strongly temperature-dependent,
so you can make conventional systems run more efficiently just by 
running them cold, at lower voltage and higher clock.

I imagine this must be pretty strongly dependent on the details of the chip:
fab-related parameters like gate dimensions, whether it's bulk or SOI, etc.

paper mentions warm-water cooling, which is indeed an interesting angle.
aquasar, for instance, is mainly aimed at reducing the delta-t
(though lower thermal resistance) while keeping chips near their 
max operating temperature.  65 degree water is somewhat useful,
but the GPU paper shows gflops/w still improving at 30 (which would
correspond with an outgoing water temp of probably around 20.)

I guess novec is available at various boiling points, for people who
want to use immersion (though one could also manipulate pressure,
I suppose...)

regards, mark hahn.

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