Introduction

Have you ever thought about how much it cost to run your PC -- the one you're using to read this article? What does it cost to play games, surf the Internet, or download files? It all costs money -- money that you, your parents, or whoever is in charge of the monthly electricity will have to pay. Those of you in charge of paying this bill will surely be interested in keeping costs down, which is why you might want to pay a little more attention to what sort of hardware you are using in your computer.

Many users -- especially computer enthusiasts -- put together a new PC that can easily handle any task, without much thought for power efficiency. If you intend to use the computer primarily for gaming, buying a high-end processor and graphics card makes sense. Likewise, if you intend to do complex three animations or movie encoding, you'll probably want to have as much processor power as possible. If all you're going to do is watch movies, run Microsoft Office, and surf the Internet, you're not going to put a big load on any of the components. In that case, your PC will typically be idle and waiting for user input, while any high-power components will still go merrily along sucking down extra power.

We recently looked at the topic of power consumption for each component in the PC. Of course the numbers were merely a rough estimate for our specific setup, programs, and tasks, so that article could serve as a baseline for the amount of power your system might require. We also discussed how power requirements affect the type of power supply that you will want to purchase. In this article, we want to focus more specifically on the costs of running a computer (not counting anything like broken components and upgrades). We look at electricity prices in the US and Europe to calculate how much various types of PCs actually cost to run. Perhaps you're one of those people with multiple systems -- one for gaming, one for office work, maybe one or two for the kids, and perhaps a few extras running distributed computing tasks 24/7. We will look at several different workloads to see how much various types of systems actually end up costing on a hourly, daily, and yearly basis.

KWh prices in the U.S and EU

When we started researching prices of electricity (measured in kilowatts hours/kWh) for the different countries, we were surprised by the huge differences in price. In the US prices range from $0.05 to $0.21, according to the Energy Information Administration -- the average price is $0.089 per kWh. European prices are different for each country, so we will just take Germany as an example. Prices there are high relative to the US but about average for Europe. In 2008, Germany has an average of 17 to 22 Cents (€) -- about $0.22 to $0.29 USD! That's anywhere from 1.5 to 6 times as expensive in the old world depending on where you live; obviously, areas where costs are higher will probably be more interested in PC power consumption, but that is a separate issue from what we are looking at today.

Calculating Power Requirements and Costs
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  • bob4432 - Tuesday, November 18, 2008 - link

    exactly, and if you are not afraid of flashing your video bios, then you can really tweak the power setups for the lower end power "2d" mode to much less than what ati put in as a default. i think ati rushed the 4850 and sounds like 4870 bios when they first came out (extreme heat, lack of real power savings, etc) but hopefully now all that is fixed.

    fwiw - i do consider the amount of $$$ in cooling when getting a real measure on how much it cost to run the pc. i am in phx, az and ac is a must, so in my computer room/office it usually gets about 5-8F warmer than the rest of the condo and therefore that difference needs to be taken into account.
    Reply
  • BitBodger - Friday, November 14, 2008 - link

    One thing not considered here is the effect of the heat from the computer. That computer sitting beside your desk is also an electric heater constantly warming your home. Live in a cold climate and this is not entirely a bad thing since it takes some of the load from your main heating system. But if you live in a hot climate and depend on air conditioning don't forget that the heater never stops meaning that your AC works that much harder and consumes that much more energy getting rid of the extra heat. And given the inefficiency of AC technology, it costs more watts in the cooling process than are emitted by the heater. Reply
  • Hammarby - Friday, November 14, 2008 - link

    In all these calculations shouldn't you also factor in how much extra it will cost to cool your house when you have a 100-500 watt space heater running for 8 hours/day?? Reply
  • Christoph Katzer - Friday, November 14, 2008 - link

    That's why the article calls "The Cost of Running Your PC"........ Reply
  • Lifted - Saturday, November 15, 2008 - link

    If "running your PC" increases the demand on your home cooling, then that is a cost directly resulting from running your PC. It is out of the scope of the article since there are too many variables to consider than just the cost of electricity. Reply
  • JarredWalton - Saturday, November 15, 2008 - link

    But if it's cold and running your PC reduces the amount of time you run your heater, then running your PC would cost less in the winter. Besides which, plenty of people don't have AC, so even in the summer there's no added expense. Thus, we chose to limit the discussion specifically to how much your PC costs to run, and how PSU efficiency can play a role in those costs. Reply
  • 7Enigma - Monday, November 17, 2008 - link

    While electricity is 100% efficient (or near enough that we don't need to quibble), it is also true that very few people use it to heat their homes due to $/BTU. Until there comes a time when it is as cheap or cheaper to heat your home electrically I don't think your comment holds true.

    I also agree with the original poster that while not exactly in the scope of the article it is closely related and should have been mentioned. The common position of why spend more money on a more efficient PSU or any other component when the electricity costs show a ROI much greater than the usable life of that product is not accurate when cooling costs are not taken into account. While heating electrically is near 100% efficient, cooling is definitely not.
    Reply
  • nilepez - Wednesday, November 19, 2008 - link

    Lots of houses are heated with electricity. I've never lived in an Apartment with anything but electric Heat.

    Nevertheless, the heat from a PSU is negligible in the winter (even in the south) and an efficient PSU, by definition, produces less heat, which is especially true when the PC is idle.
    Reply
  • ZoZo - Friday, November 14, 2008 - link

    Or you can factor in how much less it costs to heat your home when you have a 150W space heater running for 8h/day. Reply
  • Staples - Friday, November 14, 2008 - link

    I have not even read the article yet but I am surprised that was not even mentioned. That often adds 50% more to the cost if you live in a hot climate. Same thing with light bulbs. There is a double savings with CF bulbs. Reply

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