Cool it off

[Laurent Itti]

Hi Tim:

one thing that worked for us was to put large extra fans in each box; one
12cm 100cfm fan is mounted in each box using two 5.25 to 3.5 adapters (a
piece of plastic used to mount a 3.5 floppy drive in a 5.25 bay; we have
one mounted normally at the bottom, and another mounted upside down at the
top, with a 12cm fan sandwiched in between; the whole thing using 3 5.25
bays) and pushes air in; in the back, we have the power supply pulling out
on one side, and just open slots on the other side.  With that, we have
25C in the case and 29C at the CPU.

This requires some work, though...  (drill holes in mounting frames, 
buy fans at some surplus store, screw fans onto mounting frames with
fingerguard, solder power connector and piece of wire, open boxes, screw
assembly in, etc).

but it works much better than another solution we have tried, using 3
triple-fan "bay cooler" units (each has 3 tiny fans and fits in a single
5.25 bay) -- these tiny fans have ridiculously small air flow compared to
a good 12cm fan.  We did not find a commercially available equivalent of
our system.

then we have an A/C unit blowing cool air at the whole beowulf. That's
mostly so that the room does not get too hot and uncomfortable for people
(the CPU temperature alarm was preset at 75C on the motherboard and we run
at 29C, so I think the beowulf would not mind the room heating up by
another 10-20C).

check out http://iLab.usc.edu under "facilities".  The photo does not show
the fans installed yet, but I'll update it soon.

best,

  -- laurent