Target puts up a neat little article on how much juice youcomputer actually uses (they say about 100 W), here's a clip.
I was (and still am) less than thrilled with switching power supplies, but since they are here to stay, we might as well make the best of the situation. It's about time someone actually measured these misunderstood silver enclosed boxes with whirring fans. No, not dimensions, but how `bout the actual power usage. Yep, how much power does all those mysterious plug `n' pray cards and motherboard use? Whats? No, Watts!
How do you measure something like that? It's not really that hard. You need at least three things: (1) a computer (duh), (2) a current (or power) meter, and (3) someway of sneaking a peek at all those precious amps flowing through the power cord.
Ahh brings back memories of Electroinics... "ya smell that? Nothing else in the world smells like that... I love the smell of solder in the morning!"