How to choose the right power supply for your PC

Don't know which power supply to buy? In this guide, we'll go through everything you need to know to pick the best unit for your PC.

When it comes to building a custom workstation or gaming PC, the power supply (PSU) is typically one of those parts that is often overlooked, when it should be considered one of the most important components of the build. Also, many people pick a power supply based only in the total amount of wattage, assuming that the higher the number is always better, which is not necessarily true.

The power supply, as the name implies, is the component that will be supplying power to the rest of the parts, and if you don’t get a quality unit with the right wattage, you may not only end up wasting money and electricity, but you could also end up ruining your computer parts. You should never cheap out on a power supply. Selecting the right unit will ensure stability and reliability for years.

In this guide, we’ll go through the differences, some of the pros and cons, and which power supply is appropriate for any given scenario.

80+ power efficiency

Before we dive into this guide, it’s worth talking about “80+ power efficiency” that simply describes those power supplies that don’t waste a lot of electricity.

Generic power supplies are often very inefficient, and they waste a lot of electricity, even when you’re not actively using your PC. For example, if your computer requires 100 watts to operate, cheap power supplies can pull up to 150 watts from the outlet. 80+ certified power supplies work more efficiently, and they don’t waste as much electrical power.

However, depending on the efficiency level you get will result in different energy savings:

  • 80+ White is 80 percent power efficient.
  • 80+ Bronze is 85 percent power efficient.
  • 80+ Silver is 88 percent power efficient.
  • 80+ Gold is 90 percent power efficient.
  • 80+ Platinum is 92 percent power efficient.
  • 80+ Titanium is 94 percent power efficient.

It’s worth noting that above “Bronze” you’ll be only getting two percent power efficiency increase, which means that every 100 watts, you’ll be saving around two watts of electricity.

Usually, an 80+ White or Bronze power supply is what most people need. Of course, you can always go with a more efficient power supply if a good deal is available.

Also, bear in mind that your machine isn’t always pulling the total amount of wattage of the unit. Instead, the device will only pull what it needs. This means that if you typically watch videos and surf the web, your computer will probably use a couple hundred watts.

Choosing the best power supply

400 watts

An 80+ White 400 watts PSU is typically a good choice to replace a power supply of a branded computer, such as those from HP, Dell, Asus, and others, as it can handle all the components and a basic graphics card.

However, a 400 watts power supply is cheap, and it usually doesn’t include many features as you might be able to find on more experienced unit. For instance, cables are not modular with sleeves, and depending on the company you may only get a two-year warranty.

If you want a better-quality power supply that also looks better and comes with longer warranty, you may want to spend a few more dollars and get a 430 (or 450) watts PSU.

You’ll be getting 30 more watts on a different unit with better cables, additional features, and 3- to 5-year warranty depending on the brand.

500 watts

In the case that you’re planning to build, or you have a custom build PC, you should skip the White rated power supplies, and consider choosing a 500 or 600 watts 80+ Bronze unit.

Again, you’ll be spending a little more money, but you’ll be getting an 85 percent efficient power supply, which means that every 100 watts consumed these units will save around five watts of electricity over the 80+ White rated units.

In addition, you’re likely to get 3- to 5-year warranty, they have a much better appearance and quality, better cable management, and better cables overall, and either power supplies will be capable of driving a high-end graphics card, including a RTX 2060, 2070, 2080 from Nvidia, and AMD graphics like the RX 460, 470, 480, Vega cards, and newer cards such as, the RX 5500 and 5700XT.

If you’re planning to use a single graphics card from any brand, and you’re looking for a quality power supply with long warranty, a 500 or 600 watts is the one you want to get.

So, do you really need a 600 watts unit? The chances are that you probably don’t, because typically, on a basic system, you’re likely never going to go over 400 watts, even with an Intel Core i7 processor and RTX 2070 graphics. However, a 600 watts power supply will give you a piece of mind and gives you the option to install a second graphics card.

750 watts

If you have decided to invest your money well on an expensive 600 watts power supply, and you want the option to install a second graphics card, you should skip the 600 watts and go with the 750 watts unit instead.

An 80+ Bronze 750 watts unit is around $20 more than the 500 and 600 watts units, but you’ll be getting more watts and features. For example, depending on the brand, you’re likely to get either a semi-modular or modular unit.

Semi-modular or fully-modular simply means that you can connect only the cables you need. On a semi-modular unit, the motherboard cable comes built into the power supply, but all the other cables you’ll need to connect separately. On the other hand, on a fully-modular unit, you can connect all the cables separately. A modular power supply makes cable management much nicer and easier.

Semi-modular (left), fully-modular (right) power supply
Semi-modular (left), fully-modular (right) power supply

You also get a 5-year warranty, and more importantly you can install any two graphics cards on the market. Using a 750 watts PSU, you can install two RTX 2080s an Intel Core i7 overclocked processor, and your computer will perform just fine.

Beyond 750 watts

750 watts is typically the maximum wattage that most computers will need, even for gaming rigs. In order to get a unit beyond this wattage requires a significant complex system.

It goes without saying that if you’re running three or more graphics cards and more than five hard drive, you probably are going to need a 1000 watts or 12000 watts power supply.

Wrapping things up

In conclusion, if you’re looking to replace the power supply of a typical branded computer, a 400 watts would be just fine.

If you’re planning to run one graphics card, then a 500 watts power supply is all you need. In the case you’ll be running two graphics cards, a 750 watts unit is what you need to get.

The power supply brand is important. There are a lot of companies that make power supplies these days, and you should always buy from those that use quality components and offer the longest warranty.

As for which brand you should pick. EVGA are good deals because of its rating and value, and SeaSonic is another great choice that could be in the expensive side, but you’ll be getting a quality unit. Other companies you should consider, include Corsair, Cooler Master, and Thermaltake.

You can always get a Gold or Platinum rated unit, but usually the quality is the same as the Bronze, and you won’t be saving a significant amount of electricity.

In the market, you may also find more expensive power supplies, but it’s often because they offer a longer warranty.

Regardless of the wattage and brand you pick, it’s always important to consult with your motherboard manual to make sure you’re getting a power supply that includes all the cables you’ll need.

If you still can’t figure out how much wattage your device requires, you can use wattage calculator like the one offered by SeaSonic to find out how much power your system needs.

About the author

Mauro Huculak is a Windows How-To Expert who started Pureinfotech in 2010 as an independent online publication. He has also been a Windows Central contributor for nearly a decade. Mauro has over 14 years of experience writing comprehensive guides and creating professional videos about Windows and software, including Android and Linux. Before becoming a technology writer, he was an IT administrator for seven years. In total, Mauro has over 20 years of combined experience in technology. Throughout his career, he achieved different professional certifications from Microsoft (MSCA), Cisco (CCNP), VMware (VCP), and CompTIA (A+ and Network+), and he has been recognized as a Microsoft MVP for many years. You can follow him on X (Twitter), YouTube, LinkedIn and Email him at [email protected].