How to Choose a Power Supply (Simple Answer!)

How to Choose a Power Supply

Wondering how to choose a power supply for your PC? Is it automatically the highest wattage, the better? Is a power supply the first thing you should buy? These are just some of the questions people ask when looking to build their own PCs. In this post, you’ll learn everything you need to know about power supplies and choose the right one for you. 

What is a Power Supply?

What is a Power Supply

The term seems self-explanatory, but because you’re talking about a PC’s power supply, it’s not all that simple. Did you know that your PC uses DC (direct current) power? Now you do. While the power that comes from your wall socket is AC, the power supply converts this type of power to a DC power that your computer can use.

Of course, the more obvious definition of a power supply is that it supplies power to all your components, especially your CPU and GPU. It should have the correct wattage so that your components can run efficiently and that there is a minimal power wasted. 

Factors in Choosing a Power Supply

What are the factors you need to look at in buying a power supply? Here are five of those factors. 

  1. Wattage 

The first thing you have to look at when choosing a power supply is the wattage. What are your wattage requirements? To know how much wattage you need, you have to look at your CPU, GPU, and other components. If it isn’t obvious yet, each of these components uses up power so that they can function properly. Not having enough power will slow their performance; hence, slowing down your overall PC performance. 

Both the CPU and the GPU show how much power they use. They are labeled as ‘maximum power consumption’ or ‘thermal design power (TDP)’ at the back of the processors. Take note, though, that both the CPU and the GPU are just the major parts that use power. 

There are other pieces of hardware that consume power, too. However, they’re not very straightforward to compute. Fortunately, there are wattage calculators online that can help you determine your wattage needs.

  1. Efficiency 

Apart from wattage, efficiency is the next thing you should look at. As mentioned earlier, the type of power your PC gets from the wall socket is AC, but your power supply converts it to DC. During this conversion, there’s heat that escapes which reduces the efficiency of your power supply. Don’t worry, this is completely normal. What’s not normal is having an inefficient power supply. 

How do you know if a power supply is efficient? Here comes the 80PLUS rating system. The 80PLUS rating system rates how well your power supply unit converts AC to DC. The benchmark here is that a power supply that converts at least 80% is efficient. 

The 80PLUS rating system is a good factor to look for, but know that it’s a voluntary rating system. This means that not every manufacturer goes through it. Of course, it’s a lot better if the brand you’re choosing has this rating on its power supply.

  1. Rails
power supply Rails

Rails refer to the pathway of the circuit from the power supply unit to the different components. There are two types of rails - single and multi. A single rail only has one rail connection from the power supply to all the different components. On the other hand, a multi-rail has several rails with different maximum capacity on each rail.

Both have their own pros and cons. The most important thing to note here is that it is often better to have a multi-rail connection because multi-rail units’ power distribution is not equal to every component. This means that it only feeds enough power that a connected component needs. In this way, you reduce the chances of a power surge. Plus, multi-rail units also have their built-in short current protection system. 

Nonetheless, single rail connections aren’t that bad as well. As long as there is enough power given to each component, it will still run normally.

  1. Modularity

Another factor to consider is modularity. Modularity refers to whether a power supply unit is modular or not. Modular power supply has fewer long cables connected at the back of the PC. Even inside the case, there will not be a long wire clumped together. Although most people think this is just for appearance, modularity plays a role in the airflow of your PC. Think about it, the more wires stacked up inside the case, the less air gets to travel inside resulting to higher chances of overheating. 

Plus, there’s nothing wrong with wanting a more aesthetic build. Even if they’re just cables, a clean and organized case will make you feel good about your build. Just keep in mind that a modular power supply unit is more expensive than the non-modular counterpart.

  1. Expert Reviews

Lastly, but definitely not the least, are expert reviews. Whether you’re a newbie to building your new PC or you already know your stuff, expert reviews are very helpful sources of information. An important part of choosing a power supply is testing, and for those who aren’t technical, this is going to take a lot of time and effort on your end. But why go through all that stuff, right? 

best computer power supply Reviews

Instead, research on expert reviews on certain power supply units. To cut your research time shorter, identify your ideal type of power supply based on the factors mentioned above. That will narrow your search even more. It’s also helpful to stick to known manufacturers because it’s not worth it to take a chance on a low-quality power supply unit just for it to cost you even more when it breaks. 


In summary, choosing a power supply can be daunting at first, but if you start to identify the wattage requirement, efficiency, rails, and modularity, researching the reviews will be easier. Knowing the requirements of your build first will help you in determining what other features you can look for in terms of rails, modularity, and aesthetics.

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