[Beowulf] bring back 2012?

[Mark Hahn]

> Extra, the direct contact cooling stuff must still have the fans in the
> nodes to keep the dimms/disks/power supplies cool... thus use considerably
> more power than nodes without fans.

why do you say "considerably"?  1u muffin fans are annoying and not 
that efficient, but even 1U could still use blowers.  and it's not as if
you need a lot of airflow to keep 5-20W of support hardware cool.
(that would be for non-extreme numbers of disks/dimms/nics - though it 
occurs to me that motherboards also have some power regulation in them,
and if 2 sockets are drawing 250w, then 90% efficient regulation would 
still mean 28W extra heat to dissipate.)

iirc a typical 1U fan dissipates up to ~3W, but that's only when 
running full on (screaming 14krpm...).  not to mention the wide 
availability of simple 4-system-in-2u chassis (more efficient fans).