[CentOS] Off-Topic: Low Power Hardware

Mon Jan 14 16:20:56 UTC 2013
Matt Garman <matthew.garman at gmail.com>

On Fri, Jan 11, 2013 at 8:55 AM, SilverTip257 <silvertip257 at gmail.com> wrote:
> I'm in search of some hardware that consumes a low amount of power for use
> as a test-bed for Linux, various coding projects, and LAN services.
> 1) Low power consumption (10-15W ... maybe 30W at most)
> 2) Must run Linux without too much fuss (CentOS or otherwise)
> 3) Must have two NICs (fast ethernet or better)
> 4) Memory - 1GB or better
> 5) Can be configurable either via serial or VGA.
> 6) Accepts a normal hard drive, not CF -- drive capacity is my concern.
> 7) spare PCI slot is a _plus_ (extra NICs or whatever else)
> 8) I'd like to keep the physical footprint to a minimum (size of a 1U
> switch or so?)

The lowest-power x86 device I've used is an Alix 2d2 from PCEngines.
Power consumption was about five watts, regardless of load.  This has
three 100 mbps NICs, a 32-bit x86 AMD Geode CPU, and 256 MB RAM
soldered to the board.  Has a built-in Compact Flash slot to use as a
"hard drive".  I ran OpenBSD on mine for years as a
firewall/gateway/router for a home LAN (don't see why it wouldn't run
CentOS).  (I'm actually selling mine, email off list if interested.)

I upgraded my firewall device to an Atom-based D2500CCE.  IIRC, I
installed 2x2GB of RAM, booting from a cheap SSD, powered by a
PicoPSU, and running PFSense.  I think this configuration pulls
roughly 16 watts at idle, maybe a couple more watts when fully loaded.
 This board has dual Intel gigabit ethernet ports.

For my home theater PC, I'm running an ASRock H67M-ITX and Core
i3-2100 CPU, with 2x4GB of RAM and SSD.  I have it inside a Habey
EMC-800B case, using the included power supply.  Idle power
consumption is about 22 watts.  It's been a while since I measured
power consumption at load, but I'd guess 50--60 watts (it's idle 99%
of the time though).  Note that even when "idle", MythTV seems to use
a little CPU, so if I kill mythfrontend, my idle power consumption
drops another watt or two.

Only one NIC on the Asrock board, but it has a PCIe expansion slot so
you could easily add another.  I'd expect an add-on NIC to add around
one to five watts of power consumption.

My personal workstation uses an Intel DH67GD micro-ATX motherboard,
i5-2500k CPU, 4x4GB RAM, SSD, and traditional ATX power supply
(Seasonic SS-300ET).  It pulls about 30 watts when idle.  Only one NIC
on that motherboard.

For all the above, I'm talking AC (i.e. at the wall) power
consumption, in the USA (so 115 Volts), measured with a Kill-A-Watt
(not high-precision, but should be reasonable within a watt or two).
What follows is stuff with which I have no personal experience, but
have read about:

The Intel S1200KP mini-itx motherboard.  It has built-in dual gigabit
NICs, socket 1155, so you can use anything from a Celeron up to a
Xeon, depending on how much you want to spend and what your
upper-bound computational needs are.  I was considering that for my
firewall/router replacement.  With a PicoPSU I would suspect that one
could get 20 watts or lower idle power consumption.

With an Intel DQ77KB motherboard, and Pentium G2120, SilentPCReview
built a system that pulls 16.5 Watts[1].  (The article is a case
review, but power consumption information is included.)  That DQ77KB
board also has dual gigabit NICs.

You might also be interested in Intel's "NUC - Next Unit of
Computing"[2].  About 10 watts power consumption for dramatically
under-clocked i3 CPU.

In general, with modern Sandy/Ivy Bridge CPUs, it's almost trivial to
build a high-performing system that has 30 watt or less idle power
consumption.  If you cherry-pick components, it's not terribly hard to
get a system with 20 watt idle power draw.  The modern Intel CPUs all
have roughly the same idle power usage (at least the consumer line,
not sure about Xeons).  That goes for the more expensive low-power
variants as well.  The difference of the low-power variants is their
upper-bound power consumption is lower than their peers.  But you can
often fake that by deliberately limiting the max frequency in the
BIOS.  Of course, with these "real" CPUs (compared to e.g. Atom),
power consumption will be much higher when loaded.  But from what I've
read, the "real" CPUs are actually better in the long run, because
their computation efficiency is so much higher.  With something like
Atom, you get more deterministic power draw, but a severely
compromised upper-bound on computational power.  In your requirements,
you mentioned "various coding projects".  If you are working in a
compiled language (e.g. C, C++, Java), for substantially large
projects, your compile times will be painful on Atom, but pleasantly
fast on a Sandy/Ivy Bridge CPU.

[1] http://www.silentpcreview.com/Akasa_Euler_Fanless_Thin_ITX_Case

[2] http://www.silentpcreview.com/Intel_NUC_DC3217BY