So I remember hearing years ago that leaving your system on will actually end up saving you power rather than using more (as common sense probably tells you).
Then just recently, I read an article that said that it didnt matter if you turned your computer on or off for the night. It will all end up using the same amount of power. (assuming you will use your computer the next day)
I know this probably sounds like an elementary question, but does anyone know the answer to this? With todays computers, does leaving it on impact power usage?
I've heard that rumor a while ago too, and it parallels with leaving your car on saves gas. It's not true. PC's today, like varis said, don't use hardly any current in sleep, just about the same as they do just being plugged in. I haven't turned my PC off in close to a year, but it does go to sleep after an hour.
Well there are curious things in the subject of power saving. Like - switching the PSU off doesn't affect my power consumption in the above scenario (of course, you'd do that only when the system is off, not sleeping). There's still lots of room for optimization in desktop PCs, but power management nowadays is rather complex and allows various different levels of power modes for the key devices. Especially when you sleep or have variable levels of load. Power saving features are attractive to today's consumers so sleep modes get optimized and eg. my system saves over 75% energy when I go to sleep.
Monitors are another story, but seems current models are very effective in sleeping (claimed power consumption <0.5W and so on).