Power Usage

From AwkwardTV
Revision as of 03:41, 24 August 2007 by ZgzA26 (talk | contribs)
Jump to: navigation, search

bousille comici newborn sonography amd athlon64 2800 fax orion tennengebirge marcia eroi nissan x trail km 0 oakley wire 2 0 www nelly net bielyje rozy microsoft aiuta gli studenti ennio morri volo aereo cuba d-link 2100ap attenti agli occhi, attenti al... guayas volvo v40 diesel valle kosovare bootcd ps2 accessorio auto industrial equipment athlon core venice assicurazione nizza hard disk mp3 player voglio volare jeff buckley forget her lexar lettori memory card www gsi srl it arretrati dvd bomp bomp renault clio diesel corriere delle alpi belluno reflex obiettivo termometro senza contatto starsky fanck, arnold total 90 iii fg che tempo fa baladas midi dale dale don dale hercules disney lultima speranza hp omnibook portatili acer cs-5530 niina nanna orari autobus in calabria gay amateur voli antalya coppi sexy tema storico svolto golf club varese esami 2004 bowling papa gps magellan meridian videoregistratore s-vhs x destiny asus - p4c800-e deluxe - socket 478 incubo infernale united press international monitor sony 20 x-black samsung 910t mitikas philips 29 100 hz yovana coria yoshi manuali elettronica brunner, sebastian slike ferrovia centrale umbra turbamento di una minorenne tst project oh oh oh mp3 dan dailey vasco rossi senza una donna internet security suite mcafee taiwan shopping piastra in ghisa liscia tom sawyer segunda guerra mundial krhth le 7 meraviglie del mondo vicentico usted stress di notte sex teen rete di vendita diretta dj shadow in tune and on time elenco telefonico usa assicurazione bologna sottomessa morire per gioco the end in the world giochi sparatutto per due giocatori doujinshi sweet chid o mine tab football games calcio alessandria vacanza all estero check up cuore audigy 2 zs pcmcia foto volere o volare www cdf com br stryper pirgo super pene antonello de pierro adriano rome total war uscita camille claudel inno del trentino testo in italiano di frankee ricoh aficio 2018 rex fi2590fa flnc mordisco michelcamilo inno polacco fanciulla bjorg business card creator tea leoni calendari di playboy live at the blue note milan bilancia pesapersone 160 age of empires ii per ps2 bnc assicurazioni tomaselli luccio venezia catania alpi scheda madre pentium 3 fortron 350 la voglia la pazzia biblioteca j j benitez lcd 3000 nec dior fondotinta spray rey pirin y dj blass take me to the clouds laser hp stampante colori lauara pausini singstar 105 gps bluetooth 16 canali nemerix punta del este rober hatemo gurur ambasciata della repubblica del gabon in italia associazione albergatori riccione sito adulti delonghi dpw 30 antenna auto kenwood banco azteca service software v3 7 www sex sv azione freeanimalsex mature orgy north-eastern (kenya) mazzi di magic true tere backgammon office per mac 2004 italiano blog sexy cartoni animati xxx nodier, charles che ne sara di noi testo canzone donne grosse sport cubani www the n com t s t project buoni o cattivi mp3 cripte segrete calendario 2005 palmas saturno (astronomia) stazione radio priscilla lane hotel gabbiano beach vieste canon extender ef 1 4x divertiamoci hard disk usb iomega saletova osveta roosendaal en nispen sms internet gratis puntatori mouse rigoletto gilda lacie ethernet hard disk hd samsung lebt denn noch der alte holzmichel noch com e triste venezia toto maestro chat painkiller infrarossi cuffie sony auricolari e keith m maupin video nadiya perle moi nuova demo per far cry nuova bmw 320 d diesel auto nuove just cavalli abbigliamento uomo cover de andre if you love somebody cruises you are still you il tesoro del fiume sacro rossignol 9x ti oversize guns n roses dont cry == Measured power usage == Measured with Kill-A-Watt, 119V input, tested with 720p output to LCD (not plugged in to wattmeter)
Note: These figures have also been confirmed with a 240V unit.

  • Main menu: 14-15W
  • Playing a 640x480 XviD file: 17-18W
  • dnetc -benchmark2: 20W
  • "Sleeping" (white light off, no video output after holding down Play button): 14-15W
  • After a "shutdown -h now" command: 15W


  • Is there any way to further reduce power usage, e.g., disabling the graphics processor?
  • Perhaps swapping out the hard drive for a flash based card like is being done with iPod Minis nowadays?
  • What about a "Shutdown" frappliance that physically turned it off. (Realising that some sort of hard power switch would probably be needed to turn it back on).

Also as much as 30% of the power could be used by the AC-DC transformer, running straight from DC could lower the amps used.


  • Doing a pmset -g yields:
-bash-2.05b$ pmset -g
  System-wide power settings:
     SleepDisabled          1
  Active Profiles:
     AC Power                -1*
  Currently in use:
   disksleep      15
   hibernatemode  0
   displaysleep   1
   powerbutton    0
   sleep          30
   autorestart    1
   hibernatefile  /var/vm/sleepimage

So it looks like sleep has been "disabled" in the sense of traditional mac sleep. I am not super adept at the pmset command, and can't seem to find a way to reverse that setting. You are able to play with the settings currently in use (setting disksleep to 5, or 10 for example), but trying to set womp gives no results. A pmset -g cap gives you:

-bash-2.05b$ pmset -g cap
  Capabilities for AC Power:

Additional, you can directly edit the file: /Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist. At the bottom is the setting for SleepDisabled, which is set to true by default.

Note: I just changed the file so SleepDisabled is false, saved changes and rebooted. The settings were saved, and now I will see if the system goes to "sleep" on its own. I'll also report back if the AppleTV cools down at all, or if it appears the hard drive has spun down.

I have tried SleepDisabled false, but I doesn't help. The consumption is always 14-15W when idle or "switched off".

On the other hand if you "switch off" the Apple TV by holding play/pause key for 5 seconds and then you look at pmset -g there will be

   disksleep      1
   displaysleep   1

while in normal state there are zeros. The harddrive seems to sleep (I feel a delay issuing commands in commandline), but the consumption stays the same 14-15W :(

Measurement Requests

  • Power supply efficiency
    • Efficiency is measured as effective output power divided by input power (Po/Pi x 100 %). Pi can be measure as above using a Kill-A-Watt meter (you should take the Pi measurements at the same time as you measure the DC output current). To obtain Po (recall that Po = VI), first measure the DC output voltage (V) of the supply using a multi-meter in parallel with the output supply (this value should remain relatively constant regardless of what function the AppleTV is performing). Next, measure the DC current (I) using the multi-meter remembering that the meter must be placed in series with the DC output voltage from the power supply for this measurement (the output current will vary with what function the AppleTV is performing - current is proportional to processing load). Then, the output power (Po) is computed by multiplying the measured DC voltage by the measured DC current (Po = VI).
  • The digital wattmeter I have can measure P and U*I. If I remember well P=U*I*cos phi, where phi is the phase and cos phi is the efficiency. For AppleTV I have measured in idle P=15W and U*I=31VA, the efficiency seems to be comparable with my laptop power supply, where I have P=30W and U*I=60VA.