Technology Explained

How Much Power Does Your PC Need?

Joel Lee 19-05-2017

Whether you’re trying to figure out your home energy budget The Best Budgeting Apps for 7 Personality Types Which budgeting app is best? It largely depends on your personality and how you like to manage your finances. Check out these 7 apps and see which is a match for you. Read More or simply trying to cut back on your energy footprint Is Your Home Energy Efficient? 7 Things You've Overlooked The true cost of a smart home is far cheaper than you think. In fact, there are many home automation devices that everyone can afford, and many of them will feature in this article. Read More , knowing how much power your PC consumes is a crucial part of the equation. And unfortunately, this isn’t as simple as looking at the label on your PC’s rear panel.


But that doesn’t mean it’s difficult. Instead of thinking of your PC as one indivisible unit, all you need to do is look at each individual component’s energy pull. Once you know that, you’ll have a much better sense of your PC’s power usage. Here are some things to keep in mind.

Energy Usage for Desktops

While your computer is likely comprised of many different components, there are five main components that draw most of the power. You probably don’t need to look further than these parts because the power draw of everything else is insignificant by comparison.

  1. CPU
  2. GPU
  3. RAM
  4. Data drives
  5. Power supply

The good news? Finding the wattage for your PC’s components can be as easy as searching Google for each component’s model name. In particular, you’ll want to look for “technical specifications,” which should include wattage details.

CPU wattages can vary wildly. For example, take the low-end AMD Sempron 2650 APU (which is dual-core and only needs 25 W) versus the Intel Core i7-6900K (which is eight-core, insanely expensive, and needs 140 W). But for average, think of the AMD Ryzen 5 1600 (which is six-core and needs 65 W).

GPU wattages can also vary wildly. When you’re typing up an essay, it might not draw much power, but when you’re playing Crysis 3 with all graphical settings at Very High, it could be the most power-hungry component in your system. Most GPUs are rated by max pull. An integrated GPU, like the Radeon HD 8470D, may only need up to 65 W whereas the monstrous GeForce GTX 1080 Ti draws up to 250 W under heavy load.


How Much Power Does Your PC Need? gpu energy wiring internal
Image Credit: spacedrone808 via Shutterstock

RAM wattages are very low. An acceptable guideline to use is about 4 W per module. DRAM has far less static power consumption than SRAM, but energy usage can spike up to 10 W during heavy reading and writing.

Data drive wattages depend on HDD vs. SSD. For example, the Seagate 1TB BarraCuda HDD operates at between 5.3 W (500 GB and 1 TB models) and 8 W (2 TB and 3 TB models) whereas the similarly-priced PNY CS1311 SSD pulls 2.2 W when active and only 0.17 W when idle.

Power supplies can be tricky. At the very least, a power supply needs to be able to provide enough wattage for your entire system. But here’s something you may not know: the power supply pulls more power from the outlet than it provides to your system. This is because it pulls AC power (from the wall) and converts to DC power (for your PC components) and loses some energy in the exchange.


Using a power supply with 50 percent efficiency, you could be drawing 800 W from the wall to power your 400 W system. This is why a high-efficiency power supply is so crucial, and one of the main things to consider when buying your next power supply 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 .

Energy Usage for Laptops

It’s much easier to estimate the power draw of a laptop versus a desktop for one simple reason: laptop energy usage is limited to the max wattage of the power adapter (AKA battery charger). If it wasn’t, you could experience battery drain while plugged in, and that wouldn’t be a happy time for anyone.

Let’s compare the energy usage of three laptop tiers.

  • The 11.6-inch Samsung Chromebook 3 has a 40 W adapter, which fits in line with its casual user design and long-lasting battery life.
  • The 15.6-inch Lenovo ThinkPad P50 has a 170 W adapter, which is enough for its purpose as a business workstation.
  • The 17.3-inch Razer Blade Pro V2 has a 250 W adapter, which makes sense with its Intel Core i7-7820HK and GeForce GTX 1080. This thing was built to be an ultimate gaming laptop and it needs power for that.

As you can see, laptops use significantly less energy than desktops. Laptop CPUs and GPUs are specially designed to minimize energy usage (particularly when the system is idling) and these two components make up the lion’s share of system energy usage.


Also note that your laptop will only use the adapter-rated wattage under heavy loads. Most of the time, it’ll be much less. How much less? The only way to find out is to measure the energy usage yourself How Much Power Is Your PC Using? Computer power consumption can be estimated. Most of the components inside a PC have specific minimum and maximum power draw figures and, because quality control is so tight, it’s rare of a part to break... Read More , but on average, idle power usage could range from 20 W (for a Chromebook) to 50 W (for a gaming laptop).

Energy Usage for Monitors

Monitors have pretty much become a status symbol among power users. The more monitors you have in your workstation, the cooler your workstation is. This trend becomes even easier to justify when you realize that multiple monitors really do boost productivity How to Be More Productive with Dual Monitors You need space for several documents, to get an overview and swiftly shift between tasks. What's true for your desk also applies to your virtual workspace. We show you how it matters. Read More .

But if energy usage is a chief concern, you may want to reconsider. Even though modern LCD monitors are more efficient than old-school CRTs, their energy needs are still far from negligible.

How Much Power Does Your PC Need? monitor sizes diagonal measurement
Image Credit: Marcel Müller via Wikimedia


Size has a non-negligible impact. Since monitor sizes are measured along the diagonal, every additional inch actually represents an exponential increase in total screen size. For a 16:9 aspect ratio, a 21-inch monitor has a screen area of 187 inches while a 27-inch monitor has a screen area of 311 inches — a 66 percent increase, but that doesn’t mean 66 percent more energy.

For example, compare the 23-inch ASUS MX239H with the 27-inch ASUS MX279H. The “typical power consumption” of each is 22 W and 29 W, respectively, which is only a 31 percent increase. Significant? Sure. Enough to sway you towards the smaller screen? Not really.

Screen type matters. People have long recommended LED monitors over traditional LCD monitors for energy-conscious folks, and that generally holds true even today. Compare the ASUS PB278Q LED to the ASUS MG279Q LCD, where the difference is 25 W and 39 W, respectively.

So if you want to reduce energy as much as possible, go for the smallest LED monitor that won’t impede your productivity.

How Much Power Does Your PC Need? woman three monitors workstation
Image Credit: Andrey_Popov via Shutterstock

The energy savings between a 15 W and 40 W monitor may not seem like a big deal, but it adds up fast when you have a multi-monitor setup. For a simple three-monitor workstation, that’s the difference between 45 W and 120 W. For a six-monitor superstation, that’s 90 W versus 240 W. And monitors are on all the time, so you’ll definitely feel it on your electric bill.

How can you mitigate some of your monitor’s energy waste? Screensavers won’t help you save energy Are Screensavers Still Relevant? When to Use Them (And When Not To) Screensavers may no longer be necessary, but there are some really cool ones that are still worth using today. Read More . Instead, go into your operating system’s settings and set the display to automatically turn off after 10 minutes of no activity. Or even better, let your entire system go to sleep Sleep Mode vs. Hibernate Mode: Which Power-Saving Mode Should You Use? What exactly does Sleep mode do? How is it different from Hibernate mode, which is an extra option on Windows computers? Which should you choose, and are there downsides to using them? Read More . There are many ways to set this up in a way that’s convenient for you Screen Off: 5 Ways to Toggle Your Monitor & Save Energy If you're leaving your display active while your computer is idle, you're wasting energy. Here are some tools and tips to ensure that you have full control of your screen. Read More .

Adding It Up: Your PC’s Power Needs

It’s impossible to give an “average wattage” for modern PCs. A weak build that’s only used to browse the web may never cross 100 W while a top-of-the-line build that runs heavy games may need 1,000 W for hours at a time.

There are three things we can say with certainty:

  1. Laptops use less energy than desktops.
  2. Idle wattage is more than you think, so turn off your PC when not in use Pros and Cons of Leaving Your Computer Turned On All the Time It has been one of the most long-running discussions in computing: is it better to leave your PC turned on when you're not using it, or should you always turn it off? Read More .
  3. If you never do anything intensive (e.g. games, video editing), then you can save a lot more energy elsewhere. Heating and cooling are huge energy sinks The Most Energy-Efficient Way to Set Your Thermostat In the dead of winter and peak of summer, one question that pops up at least once throughout each season is: how should you set your thermostat so that both comfort and savings are maximized? Read More , for example.

Did this answer your questions and concerns? If not, feel free to chime in below. If you have anything else to add, we’d love to hear from you too.

Related topics: Computer Monitor, CPU, Hardware Tips, Multiple Monitors, PSU.

Affiliate Disclosure: By buying the products we recommend, you help keep the site alive. Read more.

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  1. This is not my name
    January 17, 2016 at 1:10 am

    Where are the editors? There are plenty of errors in this article, not to mention words that are missing entirely.

  2. Danish Nikovh
    November 29, 2015 at 6:52 am

    I really appreciate all what I've learned today regarding possible electric consumption of my desktop. I gives me the peace of mind.

  3. Anonymous
    August 12, 2015 at 2:22 am

    Citing in college report. Thank you. Good information is so hard to find. The webs big, just shallow. I would love to see more informative work like this in the future.

  4. Griffin
    December 12, 2012 at 9:14 pm

    " they often drew far power " Did you mean "they often drew far more power"

  5. Ravi Meena
    October 1, 2012 at 2:38 am

    so how does the SMPS affects the performance of a PC??

  6. Lacey Peoples Williams
    September 27, 2012 at 1:37 pm

    Nice to know thanks for the info!!

  7. Srinivas N
    September 20, 2012 at 4:22 pm

    Thanx for the article.. waiting for this kind of article on Power Consumptions

  8. bonioloff
    September 19, 2012 at 6:22 am

    Wow, great analysis..
    this website gives me something, i cannot found anywhere else i think ..

  9. Michael Jan Moratalla
    September 18, 2012 at 2:47 pm

    nice topic sir this help me a lot for choosing the right components thanks

  10. Ali Khan
    September 18, 2012 at 7:44 am

    I have a question.
    I am using Sapphire ATI Radeon HD 5870 for my gaming computer.So, is there any software which can minimized the power consuming during listening to music,surfing on net or typing documents, as these application didn't requires the processing power of GPU.
    SO,is there any software which can minimized the power usage during idle condition?

    • Matt Smith
      September 21, 2012 at 5:43 pm

      Or GPU will be at idle so it will consume a minimal amount of power during those tasks. There's no software I'm aware of that can reduce power draw for a GPU.

  11. Kao Vang
    September 17, 2012 at 5:22 pm

    Yes. I run my custom PC and used a Kill A Watt and I rarely get 300 watts, if ever.

  12. Ahmed Khalil
    September 14, 2012 at 8:16 pm

    i like this one very much, it is technical with out much complication, thanks