@lame
You are right. I missed a division by sqrt(2).

@ghettoimp
If you look at the desktop market and look what kind of grafikcards are used in modern PC just to render the eye candy of a 3D Desktop like Beryl or Aero then this is a problem. I installed Beryl once on my Workstation but quickly uninstalled it because the noisy van of my GPU drove me crazy. And that all just to render the desktop.

Any my intention is not to optimize to the last clock cycle. Design the applications well. Be careful with stuff like Hibernate that may end up in bad database performance. If you do this (what in my eyes is taken for granted) then you get better response times, your customer will be happy, your users will like you, you have better code to maintain, and finally you do a bit for the environment.

BTW: These numbers aren’t to high in my world. Some of my code is executed on machines draining up to 5.4kW. But they serve up to 3000 concurrent users with data. If you divide the consumption then these mainframes are tree-huggers…

But most computers (at homes, offices, etc.) are idle or near idle almost all the time, and they aren’t burning power because they’re busy running some application that we can optimize. It doesn’t matter if I write your word processor or web browser in C instead of Java, because 99% of the time it’s just waiting for you to type the next keystroke anyway.

A slight nitpick is that your numbers are too high. The 350W in a “350W Power Supply” is an upper bound for the power supply’s rated capacity; a typical home computer with one or two hard drives isn’t going to use more than 120 watts most of the time, then add 40 watts or so if you’re doing intense things like playing 3d games.

Lastly, you implicitly assume that energy production is harmful to the environment. That’s certainly true most of the time and in most places, but you can always build and use a clean energy source, if you’re willing to pay the price.