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You may not realize this, but your desktop computer is likely consuming a lot of power. That also means it could be responsible for raising your power bill quite a bit.

Yet, many people have a habit of leaving their desktop computer on for long periods of time. Some have even converted old PCs into home servers and media centers 7 Warning Signs It's Time to Replace your Old PC 7 Warning Signs It's Time to Replace your Old PC When should you buy a new computer? Read More , so their systems remain on 24/7. As creative an endeavor as this is, it could be using up a lot of power!

The Energy Information Administration (EIA) estimated in a 2013 report that nearly 3% of all residential electricity consumption in the United States is from computers and related equipment.

computer in sleep mode

In that same year, the residential and commercial sectors were also reported to have consumed 10.7 quadrillion BTUs of power, or 11% of all power. One quadrillion BTUs (British Thermal Unit) is the equivalent of about 293 terawatt-hours, or 33 gigawatt-years.

And it’s not just at home either. According to Dragon Systems Software Limited, approximately 50% of all office and work computers are left on overnight and during the weekends when employees are away. Even if they are in a low power state, they still consume a significant amount of energy.


The Information-Communications-Technologies (ICT) ecosystem is responsible for consuming about 10% of all global electricity consumption. In layman’s terms, that includes big data, big networks, and big corporate infrastructures.

Translation: That’s a lot of power being used by computers both at home and in the office.

desktop hardware

The average desktop computer has a total power usage rating of about 80 to 250 watts, or more if it has a stronger power supply unit 6 Things to Know When Buying a Power Supply Unit (PSU) 6 Things to Know When Buying a Power Supply Unit (PSU) Power supply units aren't as glamorous as processors and graphics cards, but they're a critical PC component that you absolutely cannot overlook. Here's what to know when buying one. Read More . Total usage also depends on the installed graphics card 5 Things You Have to Know Before Buying a Graphics Card 5 Things You Have to Know Before Buying a Graphics Card Here are five key points to keep in mind before you buy your next graphics card, otherwise you may regret your purchase. Read More  as well as any additional peripherals and hardware connected to it.

Now, let’s say a computer is running at 130 watts for 24 hours per day, 7 days a week, and 365 days a year. At a cost of about 11 cents per kW/h (kilowatt-hour), that computer will increase the power bill by $129.73 each year.

$130 a year may not seem like a lot, but it’s important to remember that’s only an estimate. Some power companies charge more per kW/h, and more powerful computers — like gaming desktops — require even more power to run. Ultimately, that means the estimate given could be much higher or lower in your specific case.


There are utilities you can use to calculate exactly how much power your computer is using. For example, Microsoft’s free app Joulemeter will show you energy usage of a Windows PC. Unfortunately, Microsoft doesn’t host the software any longer but you can still download it from CNET.

You can also use online tools like eXtreme Power Supply Calculator and Power Supply Calculator.

But desktop computers are moddable, in the sense that they all have different hardware. It makes more sense to assess your computer based on what’s installed inside. To do that, however, you would need to know the power consumption ratings of each part and which ones are consuming the most energy.

Which PC Parts Use the Most Energy?

As a general rule, the more cooling a particular component requires, the more electricity it’s going to draw. This includes hardware such as the CPU, GPU, motherboard, and power supply unit.

If you want to get technical, however, the motherboard and power supply unit merely draw power and pass it on to the other components. So, not including those, in order of how much power each component uses on average:

  1. CPU: 55 to 150 W
  2. GPU: 25 to 350 W
  3. Optical Drive: 15 to 27 W
  4. HDD: 0.7 to 9 W
  5. RAM: 2 to 5.5 W
  6. Case fans: 0.6 to 6 W
  7. SSD: 0.6 to 3 W
  8. Other hardware components: N/A

Of course, just to provide a reference, the PSU and motherboard use:

  • Power Supply (PSU): 130 to 600+ W
  • Motherboard: 25 to 100 W

Exact power consumption levels will depend on the hardware. For example, high-end AMD processors have up to eight cores and use anywhere from 95 to 125 W. On the other hand, low-end AMD processors that have up to two cores use about 65 to 95 W.

Intel processors have a totally different consumption rating, by the way.

pc monitors

As for graphics cards, when you initially look at them, they seem to be more demanding — but looks can be deceiving.

High-end graphics cards can use anywhere from 240 to 350 W of power under heavy loads, and only 39 to 53 W while idle. In reality, you’re not running your graphics card at full power all the time, just like you’re not using your processor at full power all the time.

Generally, the processor tends to be utilized more often, and so that’s why it is considered the component that uses the most power.

Added up, those components can be anywhere from 130 to 600 W or more. Settling for a happy medium, we could say the average home desktop computer runs at about 450 W.

Comparisons to Other Home Appliances

According to Michael Blue Jay — an “electricity expert” — most TVs use 80 to 400 W while powered on, depending on the size and type of technology.  Plasma TVs tend to be exceptional power hogs when compared to LCD, DLP, and OLED TVs.

home appliances

Let’s say we watch TV for about 4 hours a day, 7 days a week. At 400 W and 16 cents per kW/h, that adds up to about 0.400 x 4 x 7 x $0.16 = $1.80 per month (or $21 per year). Not bad, right?

But remember, that’s only factoring in a usage time of about 4 hours per day. If you watch TV more often, and for longer periods of time, that number is going to be much higher.

So, in reality, power consumption for the average computer is going to be about the same or slightly higher than a high-end TV.

How to Reduce PC Energy Usage

pc desktop

Luckily, there are several things you can do to lessen the amount of power your computer uses.

  1. Turn off your computer when you’re not using it (such as in the evening or on the weekends). If you’d rather have it boot faster How To Make Windows Boot Faster Than Ever Before How To Make Windows Boot Faster Than Ever Before One… two… three… how many minutes does it take your computer to start up? Hopefully not more than three, but it wouldn’t surprise me if you said it surpassed that time. The thing is, our... Read More , you can use Sleep or Hibernate instead of shutting it down completely. When in Sleep mode, your computer enters a low power state, but while Hibernating it uses no power at all.
  2. Either turn your monitor off completely when you’re not using it, or have it enter a suspend mode. While in suspend, the screen will be completely black, but as soon as you move your mouse or press a button on the keyboard it will spring back to life. Screensavers do not save power Screensavers in 2015: When You Need Them and When You Don't Screensavers in 2015: When You Need Them and When You Don't Screensavers may no longer be necessary, but there are some really cool ones that are still worth using today. Read More , so there’s no point in using them.
  3. Upgrade older mechanical hard drives to solid state drives. They are both faster and more efficient with power consumption.
  4. Unless you’re doing something that requires the extra power — like gaming or video editing — stick with onboard graphics adapters. If you have to install a video card, get something with less power. Remember, the more cooling a component requires, the more electricity it’s going to need.
  5. Replace your hardware, period. Older processors, hard drives, RAM, video cards, and other computer components are less efficient. If you have the opportunity, upgrade to newer components to boost performance and efficiency.
  6. In the BIOS, check the “ACPI Suspend Type” option and make sure it’s set to S3 as opposed to S1 or S2. This will prevent the computer from powering the CPU, RAM, and several other components when it’s in sleep mode.
  7. In Windows, under System > Control Panel > Power Options Windows 7 Power Options and Sleep Modes Explained Windows 7 Power Options and Sleep Modes Explained When Windows 7 launched, one of Microsoft's selling points was that it was designed to help your battery last longer. One of the main features users will actually notice is that the screen dims before... Read More , you can change several power saving settings including how and when your computer sleeps. This will allow you to automate the low power modes.
  8. If you don’t need a powerful computer, try swapping to a “low-wattage” version. Look at a small HTPC or media device, or even an HDMI stick PC.

Reducing Your Energy Footprint

By reducing how much power your computer consumes, you could save anywhere from $20 to $200 dollars a year. Of course, that depends on how much power your PC is using in the first place, and how much energy you’re willing to cut back on.

But more than that, you’re reducing your burden on the environment, and that’s always nice to strive for. It won’t completely eliminate that burden, but it’s a fine step forward.

Which PC-greening strategy are you most interested in trying? Or, if you have another idea for ways to make your PC use more efficient, tell us what it is! You can do both in the comments section below.

Image Credits: Outlet power strip by Virote Chuenwiset via Shutterstock, Viktor HanacekTran Mau Tri TamJoão SilasJoey Sforza and Kaboompics

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