Question about Computers and Power

[MrChupon]

I've had this question in my head for a while, and I figure someone here could answer it for me.

Do computers draw more power from the wall outlet depending on what they are doing? As I understand from portable electronics, moving parts will run down a battery faster. So I assume having your hard drive spinning all day would result in a larger power bill at the end of the month. Correct?

More specifically, I'm interesting in this will making use of your CPU cycles cost more power at the end of the month, or are idle CPU cycles costing the same amount of electricity?
I'm just curious whether all these distributed projects like Seti@home and stuff are drawing on the power grid more than an idle CPU would. Cause a CPU doens't have moving parts, right?

Thanks,
Rob

 

[MrChupon]

bump.. still curious.

 

[Vortex22]

I'm pretty sure a computer running a 3d game will use more power than an idling one.

 

[Tanked]

It takes a small amount of power to switch a transistor on or off, so if a CPU is crunching numbers, it will burn through a lot of power. An idling CPU will not switch as many transistors so it uses less power.

EDIT: Here's another way to think about it - An idling CPU puts out much less heat then a loaded CPU, and the heat produced is directly proportional to how much power it uses.

 

[MrChupon]

I see. Thanks for the responses

I'm not really prepared to stop doing distributed projects to save a few bucks on the electricity bill, but how negligable is the extra power when multiplied times a month of crunching? would it be like leaving a house lit all night? Or like Just one bulb?

 

[Alphazero]

Computers use relatively little power. More crunching will not even add up to a light bulb. However, you can save a bit more by powering down your drives when they are not being used.

 

[tk149]

Don't forget that in addition to your CPU/Motherboard/memory, you're also running your CPU Fan, case fan(s), and possibly a video card fan.

And I, too, would like to know how much it costs to run. My computer fans sound like a vaccuum cleaner (almost!), and I wonder about how much power I'm really sucking up when I run SETI. Especially since when I put my feet on my computer case, it's almost like having a space heater under my desk.