[Beowulf] bring back 2012?

[Michael Di Domenico]

On Mon, Aug 22, 2016 at 5:36 PM, Mark Hahn <hahn at mcmaster.ca> wrote:
>> 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).

i don't have any empirical evidence only 2nd hand information from
when i was an employee at Appro.  We did some serious system power
tuning for some large customers who had very stringent power
requirements.  but in any case i think your power numbers are on the
low side for auxiliary power draw in a system.