[Beowulf] longevity of 1U servers?

[Bill Broadley]

Seems like fans are the main problem with 1Us.   Pretty much efficiency (air
moved per watt) and noise (air moved per decibel) hugely favor larger fans.
I've seen 1U nodes that waste 30+ watts or so on moving air.

Seems like a rear door with a few 18" diameter fans could easily move more air
than 40 1U systems with 240 1" fans in them.  Seems like large savings in
power and expense could be had by moving the fans to the rack doors.  I've
seen blade servers basically do this, alas at a large cost premium.

Anyone seen a 1U that you could buy without fans?