Power Supplies: What You Need to Know Before Turning Your PC On

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Power supply units (PSUs) are not the flashiest part of a new computer build, and so they often go underrepresented in explainers and build guides. Many people choose a PSU based only on total wattage with the assumption that higher wattage is always better. Other people pay no attention to their power supply and just go with whatever PSU comes with their machine.

Considering how important a good power supply is to your PC’s stability and reliability, it’s vital to place just as much emphasis on your selection of a PSU as you do your graphics card and processor. Choosing a reliable, efficient power supply is possible if you know what to look for.

We’re going to take a closer look at how to identify the best power supply for your specific needs. While there is no single formula for selecting a high-quality power supply, we are going to discuss some of the most important concepts you should be familiar with as you shop for a PSU including wattage, the 80 Plus tiered rating system, and modularity of cables.

How to Determine Wattage Needs

Every PC that a customer builds is unique so the amount of power each one needs is different. For example, a high-end gaming PC will need more watts to run than a simple home office PC because powerful processors and graphics cards require more power to run.

If the PSU you purchase doesn’t supply enough power, your PC will lose power during times of intense processing. So, the question becomes, how do you calculate the amount of power you actually need? Thankfully, there are many calculators available online that you can use to calculate your computer's power needs, including Micro Center’s own PC Builder.

Simply select the parts you are using to build your computer and the Builder will compute the maximum wattage that would be best for your system. And while Micro Center’s PC Builder and other online wattage calculators will overestimate the maximum power load of your PC, it’s still not a bad idea to add approximately 10% to the wattage suggested by the calculator. Just in case you decide to add more to your build later.

One important consideration for many PC builders is that if you do rendering using GPU render engines like Redshift or Octane, be sure to plan for future GPU purchases too. Swapping out your power supply because you want to add another graphics card can be an inconvenience. If you are planning on adding another graphics card within the next 12-18 months, we recommend prepping for it right now.

The 80 Plus Tiered Rating System

80 Plus is a system used to rate computer power supplies based on their reliability and efficiency. If you don’t understand the system, you could end up spending too much money or getting a power supply that is not sufficient for your computer’s needs.

Here are the different tiers of the 80 Plus power supply rating system:

·        80 Plus Standard: At least 80-percent efficiency at all power levels and a power factor of 0.90 at 50% load.

·        80 Plus Bronze: 82% efficiency at a 20% load; 85% efficiency and power factor of 0.90 at 50% load; 82% efficiency at 100% load.

·        80 Plus Silver: 85% efficiency at a 20% load; 88% efficiency and power factor of 0.90 at 50% load; 87% efficiency at 100% load.

·        80 Plus Gold: 87% efficiency at a 20% load; 90% efficiency and power factor of 0.90 at 50% load; 87% efficiency at 100% load.

·        80 Plus Platinum: 90% efficiency at a 20% load; 92% efficiency and power factor of 0.95 at 50% load; 89% efficiency at 100% load.

·        80 Plus Titanium: 90% efficiency at a 10% load; 92% efficiency and power factor of 0.95 at 20% load; 94% efficiency at 50% load; 90% efficiency at 100% load.

While the differences between various levels of 80 Plus seem small, it requires meaningful improvements in design and component quality as you move up tiers on the 80 Plus ratings scale. As the name implies, every power supply certified by the 80 Plus standard is at least 80-percent efficient at 20-, 50-, and 100-percent of load. Additionally, 80 Plus PSUs must have a power factor of at least 0.9 at a 50-percent load. The power factor is another measure of efficiency that represents the ratio of the power going into the power supply versus the power coming out.

The 80 Plus rating system began in 2004 with the Gold, Silver, and Bronze tiers. However, because of improvements by manufacturers, higher-end PSUs are now distinguished using Platinum and Titanium ratings at the top of the scale. Additionally, a standard baseline (sometimes called “White” or “Clear” by OEMs) was added, which represents the bare minimum level of certification.

While high end PSUs such as Platinum or Titanium are available, most PC builder enthusiasts opt for 80 Plus Silver- or 80 Plus Gold-rated PSUs, as they are usually more than sufficient for the needs of their PC. That being said, if you are considering the full spectrum of PSUs, you will want to assess them based on how much noise they produce and how much they will cost. Higher-efficiency power supplies produce less heat, which allows them to be relatively quieter because their fans run less often. Some PC builders also consider the carbon footprint of their PSU. The difference in power usage could be noticeable on your utility bills, depending on how much you run your computer. '

3 Types of Cable Modularity

Power supplies are available with hard-wired (non-modular) cabling, with partially modular cabling, or with fully modular cabling. In modular power supplies, you can add or remove cabling from the PSU as needed to avoid unwanted clutter inside the case.


Non-modular power supplies have cables that are all soldered to one circuit board inside. As a result, the manufacturing of these PSUs is faster, which makes them more affordable. While non-modular PSUs do an effective job at powering your computer, the mass of cables isn’t going to make your build the cleanest. If you’ve put money and effort into buying the best PC case, you probably want to avoid having dust covered non-modular cables taking up space. However, if you are on a budget or are building a system in a case with no windows, then a non-modular PSU won’t be an aesthetic issue. That said, the cables will gather dust and airflow inside can be negatively impacted, which can create stress on your computer’s components.


Semi-modular PSUs have some but not all of the cables hardwired. Semi-modular power supplies can have primary cables such as the 24-pin, 8-pin CPU, and a PCIe cable all connected to one circuit board. Then, next to these dedicated cables, the SATA cables and, in some cases, an extra PCIe cable are modular.

There are multiple types of semi-modular PSUs including:

·        The 24pin is pre-attached while the PCIe, 8pin CPU, and other cables are modular.

·        The 24pin and the PCIe are pre-attached while all the others are modular.

·        The 24pin and 8-pin CPU are pre-attached, while the PCIe and other cables are modular.

Semi-modular power supplies help you save money on your PC build costs. With semi-modular PSUs, you don’t have to compromise as much on unused cables because you plug in most of the important pre-attached cables.

Fully Modular

When it comes to fully modular power supplies, all the cables are individually seated. This means airflow is greatly increased thanks to a reduction in cable cluttering and extra sockets to seat the cables into the PSU. As a result of the reduced amount of cabling, there is less dust build up. This, in turn, results in lower temperatures and less fan usage.

From an aesthetic perspective, you won’t have a bundle of cabling in the middle of your case because only the cables you require will be used. Also, fully modular PSUs are compatible with different colored power cables, which gives you a bit of extra design flair with your build.

Micro Center Has Your PSU Needs Covered

Would you like to know more about which type of PSU is right for your PC? Visit your local Micro Center and talk to our helpful associates today!

More from the Micro Center Community:

Looking for more information about Building a PC? We’ve got PC Build Guides as well as articles on How to Choose Parts for you Custom PC BuildProduct Reviews, and Part Comparisons. And if you can’t find what you’re looking for, don’t hesitate to post a new discussion and the Community will be happy to help!

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