How much does a running computer cost on the electric bill?

[Parker03GT]

I've always been in military housing so we don't pay electric bill. However, I'll be out soon and just upgraded to a computer requiring a 550W power supply. Is there a formula for calculating how much it would cost me in electricity if I were to leave it running 24/7 as opposed to turning it off every time I'm not using it? Even at that, isn't a computer kind of like a car engine in that it's hard on the equipment to constantly turn on and off?

[mbossman2]

running 24 hours a day, 7 days a week?

figuring $0.06/kWh at maximum usage continuously 24 hours a day (unlikely) = 13.2kWh/day ( (550 * 24 hours)/1000 ) = $0.80 a day * 30 = ~$23.76/month

reality? with power management for half the day, figure $15 or so a month (half the day at full power, the other half at half power)

$0.06kWh is a rough estimate of AZ electrical rates

[doctorgonzo]

Keep in mind too that computer PSUs, being switching power supplies, only provide the energy the computer needs. It's not providing 550W all the time unless necessary.

Just for comparison, I run two computers 24/7, and my total electricity bill is around $30.

[12twelve12]

Just want to say thanks to Parker for posting this question...I always wondered about this myself.

[David M]

Just to clarify something..a Kilowatt-Hour or KWH is is a unit of energy. It is the equivalent of running ten, 100 watt lightbulbs for one hour. If you have never paid the electric bill, this is how the power company charges you.

If you have a killer gaming machine and it draws 500 watts during an intense 2 hour session of Battlefield and you are being charged 6 cents per KWH then it will have cost you: 0.5 KWH x 2 hours x 0.06/hour = 6 cents.

Cheap thrills

[colecifer]

Originally Posted by David M Just to clarify something..a Kilowatt-Hour or KWH is is a unit of energy. It is the equivalent of running ten, 100 watt lightbulbs for one hour. If you have never paid the electric bill, this is how the power company charges you. If you have a killer gaming machine and it draws 500 watts during an intense 2 hour session of Battlefield and you are being charged 6 cents per KWH then it will have cost you: 0.5 KWH x 2 hours x 0.06/hour = 6 cents. Cheap thrills

Well the power is cheap, but the game and machine not so much.

[Parker03GT]

Originally Posted by 12twelve12 Just want to say thanks to Parker for posting this question...I always wondered about this myself.

I'm here for you people Thanx for all the replies. My wife brought this up the other day cause I leave the comp on all the time except when we go to bed. She said that I'll have to start turning it off all the time when I don't use it because of the electric bill. The irony is that she's the one that leaves lights & tv's in other rooms on while she stays in another room

[~LP]

Because I'm a Folder and folders like to know theses things ~

Around my neck of the woods (Midwest), it costs approximately $6 a month per tower, to run 24/7 @ 100% cpu usage.
Your mileage will vary with electric rates in your area, and usage.

[sdkfz]

If you set your power options to turn off the monitor and hard drive after some time you'll cut that cost- especially if it is a CRT monitor - they use a lot more energy than a LCD. You also could go to the next step and have it hibernate which will cut the power use even more. I use this and AV scans etc still kick in as expected.

[Cricket]

Desktop CPU Power Survey, April 2006

Cricket

[David M]

You can find out with certainty how many watts your computer is drawing by using a clamp ammeter and getting a splitter that divides the hot and neutral at the wall socket. Place the ammeter over the hot or neutral leg of the splitter and measure the current. Take the current and multiply it by the voltage at the wall socket which will give you the number of watts your computer is drawing. It's really that easy and and it does not involve any complex tables or formulas...which are just guessing at the number of watts your computer draws.

[HAL9000]

I really don't think it costs that much to run a computer 24/7. I'm on an equalized electric bill which sets me at a constant bill every month. Now keeping in mind, I have a wife and daughter that understand the on switch for lights, but never turn them off, 2x TV's that run for the majority of the day. I run AC in the summer, dishwasher going daily, been using a lot of electric heat in the garage for some work I've been doing in there. My usage for 32 days according to my bill was 793Kw/h. I have THREE computers running 24/7... now given mbossman2's estimate (yes, I realize it's probably an over estimate) of 13Kwh/d x 3 x 32 = 1248Kw/h, almost double my actual usage... so you can see, they're obviously using a LOT less than that... even to say 1/4 of that would be too much yet.

[mbossman2]

the one thing that i couldn't account for was the energy star low power usage and actual usage time...

according to the energy star site, it looks like an idle PC runs at about 70w when in low power mode. figuring that most folks use their computer about 10% of the time and the rest of the time is on power down...then you would get something like $4-6 a month range....

[HAL9000]

Those numbers, on the low side are MUCH more believable