How much electricity is used?
In each of the following cases, please label the electricity used as (A) very little (less than 1 dollar a month), (B) moderate (between 1 and 5 dollars a month), (C) high (between 5 and 10 dollars a month), or use your own words.
- Leave my computer in standby mode.
- Leave my computer in hibernate mode.
- Turn off my computer but the cord remains plugged.
Since I don't have a good computer to use for direct measurement, I'll use Wikipeda and compreviews.about.com as my sources for power consumption calculations.
First, in my area a "month" is considered to be a period of 30 days, so I'm going to use that for calculations. So 30*24=720 is the number of hours in a month. Next step is to determine power consumption of a device in watts and multiply.
So they say that on PC which is Energy Star certified (and I don't remember when I've seen one which isn't), power supply can't use more than 2 W when in stand-by and more than 4 W when in sleep. I'll take 4 W for calculation purposes.
So 4 W * 720 h = 2880 Wh = 2.88 kWh. We multiply that by the energy price, so we get:
2.88 kWh * 0.1135 $/kWh = 0.32688 $.
That means that all answers are A), since hibernate and power-off can't spend more than sleep.
If the cord is unplugged then it cant be pulling any power. Hibernate also doesn't require any power since the machine saves your state to disk.
Standby requires power to keep data in memory, although it is the fastest state saving option due to memory access tims vs disk I/O times.