Posted by Bjoern Michaelsen on 20 August 2013


I've got the power.

-- The power, Snap

So, Im back from vacation. One of the things I did was reorganizing my hardware, and for doing so, I bought a wattmeter to measure what my machines and toys actually consume. A lot of the stuff was what I expected, but there where a few nasty surprises:

 (all values in Watt) Ideapad S12 Thinkpad W520 Bertha TV Pandaboard ES
power supply only 0 0.2 2.5 0.3 0.1
standby 0.3 0.2 2.5 15 3.2
desktop w/o display 13 10 122 130 6.1
with display 18 16 180 100
g+/gmail 20 20 212
compiling 90/70/35 417 8.1
From this set a few surprising takeaways:
  • The wimpy Ideapad S12 with its Atom CPU eats more power when idling than the Thinkpad W520 with its beefy i7 Quad-Core and 16GB of RAM (13 Watts vs. 10 Watts).
  • My TV doing nothing but waiting for the remote to tell it to turn itself on eats more power that each of my notebooks (15 Watts vs. 10/13 Watts).
  • Just opening Firefox with one tab google plus and one tab google mail eats 4 extra Watts on my notebook and 32 extra Watts on my desktop. It seems all that JavaScript voodoo does not come free at all: ~6 Euros per month when I leave it open on my desktop all the time.
  • Running my desktop (Bertha) as an tinderbox for LibreOffice 24/7 would cost me ~1.000EUR per annum. Doing it with three of those boxes would a very expensive and noisy alternative to what others sell as a room heater.
  • My TV eats 30 Watts more when displaying the black screen of a disconnected HDMI signal than with normal TV display. Maybe its expensive to search for a signal?
  • Compiling LibreOffice without ccache on my Notebook kicks the power consumption to 90 Watts -- but only for a few minutes. Then the thermal controls throttle the machine down to 70 or even 35 Watts, which seems all the machine can disperse over sustained periods.

![My electricity is 100% from water power, btw. Admittedly -- its unlikely to come from the Hoover dam, though (Image copyright CC BY 2.0 by Gordon Wrigley)] (http://farm8.staticflickr.com/7092/7067177993_4989070568_c.jpg)

And then there where these leftover pieces to measure, no surprises there, just a confirmation of my suspicion that the old Asus notebook I run as a home server is eating way too much power:

(all values in Watt) bits and pieces
mic preamp off 1.1
mic preamp on 10
hub 5
phone 4
"home server" (decommissioned Asus Z53 notebook) 30
My tentative conclusions are:
  • replacing my old "home server" with something ARM-based like a Raspberry Pi or a Pandaboard breaks even after one year -- I should do that.
  • Even when under load, a ARM-based Pandaboard has a modest power consumption.
  • I will completely turn off my TV on principle as the standby consumption is just pure impudence. As a bonus it prevents my BluRay player from kicking on the 100 Watt TV when I throw in a audio CD (Thanks Panasonic, for providing this excellent and "useful" integration).
  • A cheap Netbook might be less powerful, but it hardly consumes less than a high-end Notebook when idling. You get what you pay for.
  • I bought a cooler for my Notebook, hoping to unlock it from choking itself with thermal restriction. It should be a good idea in general as the logs not only talked about throttling, but also about more scary MCEs.
  • Buying a wattmeter is a good decision, when you run nontrivial amounts of hardware.
Addendum: The 2.5 Watts for Bertha when off may seem bad -- but its not at all, if you consider it is running a lights-out management on that.

Originally published on 2013-08-20 17:06:18 on wordpress.