Saturday, August 30, 2008

Notes on My Own Power Use

I live an electrically powered life. I spend most of my days with computers, mp3 players, and high definition televisions and gaming consoles. In spite of being surrounded by all these devices, I had never really paid attention to how much power they use. When I decided my desktop computer's video card was going to need an upgrade eventually, I realized that I had to know exactly how much power it was pulling so I could tell if the power supply had enough overhead do the upgrade. That was all the excuse I needed to pick up a meter that could measure power draw. And hey, once I owned the meter, I could learn what all those other electronic devices were up to.

I'll start with the desktop computer since it was my primary concern and makes a good comparison point. I assembled it myself from parts about a year ago, and I did have efficiency in mind. I guesstimated what the smallest power supply I would be able to get away with was, so I was worried that in the world of kilowatt power supplies, my 380 Watt beauty wouldn't cut it. The numbers happily showed that I had nothing to fear:
  • Power off: 3W
  • On and idle: 83W
  • Central Processing Unit loaded: 129W
  • Graphics Processing Unit loaded: 134W
  • CPU & GPU loaded: 149W
  • Full load (CPU, GPU, Memory, & Hard Disk Drive): 161W
As usual for a gaming capable machine, the GPU can draw more power than the CPU. The important numbers are the idle and full load measurements, which represent essentially the low and high points of the power curve when the machine is in use. I was interested to see how those compared to other household items, so I did some more measurements:
  • 1W: electric alarm clock
  • 3W: computer (laptop or desktop), turned off
  • 4W: wireless router
  • 5W: cable modem
  • 13W: 16W Compact Flourescent Lightbulb (CFL, 60W incandescent equivalent)
  • 27W: 26W CFL (100W incandescent equivalent)
  • 25-30W: laptop computer, idle
  • 34W: entertainment center, turned off (HDTV, DVR, XBox 360, and stereo receiver)
  • 45W: laptop computer, loaded
  • 54W: 60W incandescent lightbulb
  • 83W: desktop computer, idle
  • 102W: 100W incandescent lightbulb
  • 158W: toaster oven toasting
  • 161W: desktop computer, loaded
  • 280+W: entertainment center, everything on and active
Of course, these numbers are just spot measurements in my house, but I think the relative size is illustrative. My laptop computer under light load (say, typing a 'blog post) uses about the same amount of power that my TV setup does just sitting there off. CFLs really are that much more efficient than regular bulbs. My computer can produce more heat in a given amount of time than my toaster oven...

1 comment:

Lee said...

I found this absolutely fascinating. Yes, I am a nerd, and proud of it.

I know all these devices draw power when "off" but it still surprises me how much it adds up.