Tech Guided is supported by readers. If you buy products from links on our site, we may earn a commission. Learn more

How to Choose A Power Supply: 5 Things to Know Before Buying A PSU

How to Choose A PSU
One of the most difficult components for first-time builders to choose is their power supply. Power supplies won’t improve your framerate and they aren’t really a big part of your system’s aesthetics. However, there is no component more central to your system’s long-term health than your power supply.

If you choose a low-quality power supply, your build will either not run, or it will suffer over the long term.

On the other hand, if you don’t understand how much power you need in order to efficiently power your system, you could end up allocating more of your budget towards your power supply than is necessary and, as a result, lose out on actual system performance.

In this article, we’re going to discuss five different factors that you should consider before choosing a power supply. Understanding these five points will help you pick the right power supply for your budget and needs.

Figuring Out the Correct Wattage for Your System

Before you choose a power supply, you need to first figure out how much power you will actually need from your power supply in order to run your computer

You can do this in a couple of ways:

  1. Find power draw benchmarks from sites like Tom’s Hardware on the components in your system (mainly, you’re GPU and CPU) and add them together to give you a minimum wattage rating.
  2. Use OuterVision’s power supply calculator.

In my opinion, OuterVision’s power supply calculator is the much easier and less time-consuming method for determining how much power your system will actually need.


All you have to do is use the drop-down menus provided to enter in your components into the calculator and then hit the calculate button to see what the recommended PSU wattage is for your system. With the ‘Expert’ tab you can even account for overclocking on both your CPU and graphics card as well.

OuterVision’s calculator is probably the most accurate calculator out there. Other calculators I’ve tried end up suggesting wattage ratings that are much higher than you actually need. As a good rule of thumb, though, it’s not a bad idea to add some headroom onto the number that OuterVision gives you. So, if it tells you that you need a 450W power supply, going with a 500-550W unit isn’t a bad idea.

A High Wattage Rating Doesn’t Equal A Quality Unit

Just because a power supply is listed as a 600W unit (as an example) doesn’t mean it can deliver that amount of power over a long period of time.

A lot of no-name PSU manufacturers list their power supplies at wattage ratings that are much higher than what they can actually deliver over a given period of time. Some first-time PC builders make the mistake of thinking that just because a power supply has a high wattage rating, that means it is a good enough power supply for their needs.

And, because a lot of these low-quality power supplies come in at ridiculously low prices, some make the mistake of thinking they are getting a solid power supply for a great price. The reality, though, is that they are purchasing a very bad unit that has a misleading wattage rating.

So, it’s important to avoid no-name power supply manufacturers and just stick to well-known manufacturers. Here’s a quick list of manufacturers who are known for making quality power supplies:

  • EVGA
  • Corsair
  • Seasonic
  • Antec
  • Cooler Master
  • Silverstone
  • Thermaltake
  • be Quiet!

This, of course, is not an end-all list and it’s important to note that not every power supply from the manufacturers listed above are quality units. So, it’s important that once you have a wattage rating, that you do your due diligence in researching what quality units are available in your price range.

The best way to do that is to read expert reviews or check our curated list of quality power supplies in our PSU Buyer’s Guide.

The Importance of Expert Reviews on Power Supplies

Testing a power supply is a bit more involved of a process as compared to testing/benchmarking other components. Take a look at the testing methodologies from sites like Tom’s Hardware.

As you can see, a lot of extra equipment is used in their power supply tests. And, some of that equipment is fairly expensive.

And, because the process of testing power supplies is a bit more difficult than testing other components, there aren’t as many power supply reviews out there as there are reviews on other components.

Fortunately, there are a handful of reputable power supply reviewers out there. Here are a few of them:

Before you purchase a power supply, it’s a good idea to check and see if any of the above websites have done a review on it first.

Explaining The 80 Plus Rating System

Another factor you’ll need to consider when choosing a power supply is the different 80 Plus efficiency ratings.

From Wikipedia:

80 Plus (trademarked 80 PLUS) is a voluntary certification program intended to promote efficient energy use in computer power supply units (PSUs).

To further understand the 80 Plus rating system, you first need to understand a little bit of how a computer power supply works.

Also Read: 80 PLUS Bronze vs Gold vs Platinum vs Titanium: Which PSU Rating do you Need?

Your computer’s components use DC (direct current) power. However, the power coming from the outlet that your computer is plugged into delivers AC (alternating current) power.

Your power supply is responsible for converting the AC power from the wall into the DC power that your components need to operate.

During this conversion, there is some loss of power to heat. So, 100% of the AC power drawn from the wall does not get converted into DC power. A decent power supply will convert at least 80% of the AC power it draws from the wall into DC power.

A really good power supply will convert 90% or more.

The 80 Plus rating system basically tells you how efficient a power supply is at converting AC power into DC power. But, it goes a little deeper than that, as the 80 Plus rating system judges a power supply’s efficiency when it is under specific loads.

In order to earn one of the 80 Plus badges, a power supply must maintain a specific level of efficiency when it is under 20%, 50%, and 100% load. (The newest 80 Plus rating, Titanium, considers a power supplies efficiency when it is under 10% load.)

Here’s a table that breaks down each of the different 80 Plus ratings and what efficiency level it needs to reach in order to qualify for that specific rating:

80 Plus Rating Levels 115v non-redundant
% of rated load 10% 20% 50% 100%
80 Plus 80% 80% 80%
80 Plus Bronze 82% 85% 82%
80 Plus Silver 85% 88% 85%
80 Plus Gold 87% 90% 87%
80 Plus Platinum 90% 92% 89%
80 Plus Titanium 90% 92% 94% 90%

It’s important to note that the 80 Plus rating system isn’t perfect and doesn’t necessarily indicate that a power supply is a quality unit. And, therefore, it shouldn’t be used as the main determining factor in the quality of a power supply.

However, it is true that power supplies that achieve the higher spectrum of 80 Plus ratings (Gold, Platinum, and Titanium) are generally well-built and quality units. But, just note that, if you are in the market for a power supply, it’s a good idea to consider the 80 Plus rating system of a unit in conjunction with in-depth reviews on that same unit.

A Quick Note on Power Supply Aesthetics

For a large portion of people who build their own computers, aesthetics play an important role in the component selection process. However, power supplies are one component where aesthetics usually doesn’t play a large role.

Yes, there are RGB power supplies out there. And, there are power supplies that look better than others.

However, for me, the main thing I look for in a power supply in terms of aesthetics is mainly its cabling/sleeving.

You can spend a lot of time ensuring that your other components are color-coordinated and you can have the cleanest cable management around and you can show it all off inside of a case with a nice full-glass side panel.

However, if your power supplies cables look like this…

multi-colored cabling

…the multi-colored cabling is going to take away from the aesthetics of your build and your system won’t look as nice as if your power supply came with all black cabling like this…

black cabling

If you don’t care about aesthetics, obviously you don’t need to worry about the color of a unit’s cabling. And, if you are purchasing a modular unit, you can always swap the cabling out for custom sleeving, too.

Also Read: What is A Modular Power Supply? Modular vs Semi-Modular vs Non-Modular

However, if you are budget-oriented, but you still want to build a nice-looking build, just know that of the more affordable power supplies out there, there are some units that will have all-black cabling that won’t take away from your build.

So, while aesthetics aren’t a major thing to consider when buying a power supply—especially at the higher end of the market—the cabling, to me, is an important aspect that you might want to consider if you are looking to build a clean-looking system.

Choosing the Right Power Supply

While power supplies might not be the sexiest components in PC builds, they are one of the most important. In this post, we’ve given you five things to consider when choosing a power supply for your build.

If you take these five factors into consideration, you’ll have a much easier time choosing the right PSU for your needs.

Hey, I’m Brent. I’ve been building computers and writing about building computers for a long time. I’m an avid gamer and tech enthusiast, too. On YouTube, I build PCs, review laptops, components, and peripherals, and hold giveaways.

6 thoughts on “How to Choose A Power Supply: 5 Things to Know Before Buying A PSU”

  1. Hi team, I need help choosing a PSU for my future 3D build workstation. Here is my config:
    AMD Ryzen 9 3900XT
    AMD Radeon Pro W5700
    4× 32 Go DDR4 3200 MHz
    2 x M.2 NVMe 4.0 ( 500Go + 1To)
    2 x 140mm FAN
    5x 120mm FAN

  2. I need help finding a power supply My build contains the following
    Nzxt h510, ryzen 7 3800x , MSI mpg x570 pro carbon WiFi (entry level) , 2×16 rgb pro ramsticks 3200 MHz
    2 stock fans from case and 2 Corsair icee fans all 120mm, GPU is the red devil Rx 5700 xt , with a 4 tb hard drive. 7.2
    What power supply do I need . I’m lending towards Corsair psu’s

  3. Can u help me?
    I want to buy a power supply with the brand deepcool da700 80+ bronze. is it running normally for radeon rx 5700?

    Pls answer.

  4. Hi, just a thank you for the comprehensive yet concise article with technical content made accessible through well structured writing that lead me from ignorance to enlightenment (regarding my PSU hunt at least) in seconds, and wider kudos for the site as a whole. Such a rarity to find quality content, especially without pop ups, affiliate links and sponsored content.

    Thank you

  5. Outstanding piece of work. One of the best instructional pages for buying a PSU I’ve seen, as I prepare for my new build. Thank you!


Leave a Comment