Save energy: use Linux
josip at icase.edu
Mon Sep 25 15:43:47 PDT 2000
Jared Hodge wrote:
> We're looking at upgrading our beowulf using the 370DLE, 800EB Mhz
> processors (one per node to start) and 512MB RAM. If anyone has
> suggestions or warnings, please let me know.
You need at least 300W power supply (350W preferable, with ATX 2.03
auxiliary power connector). Otherwise, you could draw more than 50% of
peak current rating at +3.3V and +5V rails. Most power supplies assume
that nominal load is about 50% of peak load.
We've measured our new node AC current requirements today (node = 370DLE
+ dual P3/800EB + 1GB RAM + Giganet cLAN + tulip NIC + 30GB EIDE drive +
floppy + PCI video card). Here are the results (all AC measurements are
current surge when first plugged in: 2.0 A approx.
current when switched on: 1.02 A max.
current when idle: 0.66 A typ.
current when normally loaded: 1.0 A typ.
current when VERY heavily loaded: 1.24 A max.
power voltage during test: 123.5 V typ.
Assuming 70% power supply efficiency and assuming that our fans and disk
drives draw about 20W at +12V, I'd say that our units use less than
about 90W of combined +3.3V/+5V power. For reliability and durability,
you'd want a power supply with about 160-180W combined power rating. A
300W power supply typically delivers 160W of combined +3.3V/+5V power
(which is probably sufficient), while some 350W units boost this to
BTW, here is the amusing bit of information which prompted the subject
line change: Linux is more power efficient than Windows! On my loaded
dual CPU box, Linux draws 0.74 A at idle, but Windows NT 4.0 requires
1.14 A at idle. This means that you can save about 48 W of electricity
by switching to Linux.... Perhaps Linux should get the 'Energy Star'
P.S. I know, V*A is not W, but W <= V*A when RMS measurements are
used. We were concerned with upper limits anyway...
Dr. Josip Loncaric, Senior Staff Scientist mailto:josip at icase.edu
ICASE, Mail Stop 132C PGP key at http://www.icase.edu./~josip/
NASA Langley Research Center mailto:j.loncaric at larc.nasa.gov
Hampton, VA 23681-2199, USA Tel. +1 757 864-2192 Fax +1 757 864-6134
More information about the Beowulf