When building a PC it is easy to get overwhelmed by the sheer number of options available. Not only does every PC need several components that all must be compatible with each other, each component, whether it’s a case, a GPU, or a PSU, includes several possible options and it is often unclear which you should choose and why. For PSUs specifically you will see several different wattages, efficiency ratings, form factors, and other options that can make it rather difficult to determine what is right for your build.

Below, we have compiled a list of the 3 most important factors to consider when choosing a PSU for your build. Note that this list is not exhaustive and there may be other factors for you to take into consideration. However, for most builds, these three things will be the most important.

1. Wattage

Undoubtedly the most important step in selecting the right PSU is figuring out how much wattage you need. If your PC requires 1000 watts but you have a PSU that can only handle 600 watts, your PC won’t even turn on. Thus, after you have decided on a GPU, CPU, motherboard, RAM, and storage solution it is recommended you use a PSU calculator to get an estimate of how much wattage your PC will require.

From there, it is a matter of determining how much more wattage you want than what is recommended. Generally it is a good idea to go with a PSU that has an output around 100 to 150 watts higher than your estimated requirement, to be on the safe side. Cooler Master’s GX III Gold is a top-of-the-line PSU with a particularly broad range of wattages, from 650W to 1250W, capable of supporting a wide variety of builds.

2. Form Factor

In previous articles, we have described ATX and SFX PSUs, and the differences between the two. Determining which PSU form factor you need largely comes down to your selected case and overall preferences. If you are building a smaller form factor PC with something like a mini-ITX case, you will not be able to use an ATX PSU. If your case is particularly large and you want to use an SFX PSU, you will need to ensure that you have an adapter bracket and that the cables are long enough to reach each component. Units such as the V SFX Platinum come with an included ATX-compatible bracket.

Think first about what kind of PC you want and what size you want it to be. Then determine which PSU form factor, ATX or SFX, is most compatible with your case. Most commonly, builders go with an ATX PSU for an ATX case, or an SFX PSU for an ITX case. However, if you are unsure or simply want to keep your options open, go for an SFX PSU with an ATX-compatible bracket.

3. Efficiency

An inefficient PSU can cause serious problems for the long-term performance lifespan of your machine. The more inefficient a PSU is, the more power is wasted and the more excess heat is produced. Luckily, determining a PSU’s efficiency is made very easy by the standardized 80 Plus certification system. This system utilizes metals to indicate level of efficiency. The rating system is as follows, from least efficient to most efficient: 80 Plus, 80 Plus Bronze, 80 Plus Silver, 80 Plus Gold, 80 Plus Platinum, 80 Plus Titanium.

Ideally, you will be able to find a PSU for your build that has a Gold certification or higher. For example, Cooler Master’s V SFX Platinum is highly efficient, while the GX III Gold can achieve Titanium level efficiency at light loads despite its Gold certification.


As you can see, choosing a PSU isn’t so daunting as long as you keep these three important factors in mind. There are many options out there, but ultimately only a handful of them are compatible with your specific build. Check your build’s wattage requirements with Cooler Master’s handy PSU calculator, know your case’s form factor, and research each unit’s efficiency rating, and you will be well on your way to finding the PSU that is best for you.

For a look at Cooler Master’s own wide selection of PSUs, check out this link.

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