How to Choose a Power Supply?

How to Choose a Power Supply?

A power supply is one of the most important components of any PC since it provides power so you can operate it. But if we look into a deeper perspective, the power supply unit or PSU converts the high-voltage AC current into a lower-voltage DC current to make it more suitable for the computer’s components like processor, graphics card, RAM, and others. No doubt, the power supply doesn’t directly add some value to the PC’s beauty or improve frame rates while playing games. Rather, it plays a key role to keep running the system by transmitting optimal power. 

For your information, several first-time builders often forget the importance of this component since they don’t know how to choose a power supply. An unsuitable power supply can produce unnecessary heat and lower efficiency levels as compared to a good-quality power supply. Moreover, if the power supply is damaged it can also damage the components of the computer. Well, if you are facing such issues or just want to buy a new power supply, this post can help you. You must read all the necessary factors given below to make a better choice. 

Check Compatibility First

Form factor

Like any other tech-related product, a power supply comes with a certain form factor—the form factor is the overall dimensions or physical size of the unit. But there is a huge variety of power supplies with a long list of sizes so you need to consider this factor important if you don’t want to put your money into an incompatible power supply. For your information, you can find power supplies with standard ATX, EPS, SFX, and many others to help you build your custom PC with the required power supply.

The ATX PSU would be fine for a wide range of current-era computers unless this size doesn’t cause any type of size-wise incompatibility. In addition, if you’re building a small form factor or SFF PC, you need to have a compact power supply to fit it into the system. In such a case, you can check out SFF PSU sizes like SFX, CFX, and a few others since these are smaller in size. Overall, this factor is on the list to make you ensure to check the PSU spot inside the PC case and purchase accordingly. 


After ensuring an appropriate form factor, the next step that you must consider is the cabling preference. No donut, the connectors on a PSU are critical to its function, and the cables connecting your PSU to other components in your computer have features that can help simplify cable management and personalize your computer. All power supply cabling comes in three styles: modular, semi-modular, and pre-installed. So let’s check out the different types of power supplies first before deep diving into the factor!

  • Modular: Modular power supplies save space by allowing users to connect a minimum of cables for each device. The modular design helps with cable management and adds the option of personalization with custom cables.
  • Non-modular: Non-modular PSUs have all necessary cables pre-installed on the power supply, and are not removable. These units can be simpler to build but often clutter the case with dangling cables or unnecessary connectors.
  • Semi-modular: Semi-modular power supplies are a combination of the above two styles, with some cables already installed but room for the customer to add more as needed. This is the only reason that makes it different from the other two types. 

No doubt, the non-modular PSUs are more convenient since they come with pre-connected cables and connections to save time. In contrast, the modular power supplies need to be properly wired by the user so it may be complex for some users. But if you know how to do your job, you can optimally connect different cables, saving a lot of room. In this way, you can make the overall airflow better which will ultimately make the thermal management better. In short, you must consider all these factors for a power supply. 

What is the 80 Plus Rating system?

Another factor that you must consider when choosing a power supply is the various 80-plus efficiency ratings. If I simplify the topic, the 80 Plus system is used to rate and differentiate different power supplies or PSUs depending upon their efficiency and reliability. In this way, we can easily understand the versatility of a particular power supply and decide whether it’s good for us or not. As a power supply converts the high-voltage AC current to low-voltage DC current so different elements operate properly. The 80-plus rating system basically tells you how efficient the power supply is at converting AC power to DC power. 

In addition, it goes a little deeper than that, as the 80 Plus rating system tests the power supply’s performance when it’s under a specified load. To earn one of the 80 Plus badges, the power supply must maintain a certain level of efficiency when under 10%,  20%, 50%, and 100% load. For your information, the latest 80 Plus rating, Titanium, considers power supply efficiency at less than 10 percent load.  It means that 100% of the AC power drawn from the wall is not converted to DC power rather a decent power supply will convert at least 80% of AC power from the wall into DC power.

Here’s a table that breaks down each of the different 80 Plus ratings and what performance level one needs to reach to qualify for that particular rating:

Rated efficiencies 10% load20% load50% load100% load
80 Plus Bronze82%85% PFC ≥ 0.9082%
80 Plus Silver85%88% PFC ≥ 0.9085%
80 Plus Gold87%90% PFC ≥ 0.9087%
80 Plus Platinum90%92% PFC ≥ 0.9589%
80 Plus Titanium90%92% PFC ≥ 0.9594%90%

Check Certification or Badge 

When choosing a power supply unit (PSU) the things to consider are its performance and certification. Efficiency is measured in % load efficiency which indicates how much energy it dissipates under different loads. When you are shopping for a power supply you can choose to filter by 80 plus certification level. This makes it easy to dial in the exact same level of performance in your new PC. The 80 Plus Titanium is the most excellent badge since such power supplies provide the most excellent power ratings. But you take help from the table given above to choose one. 

How much power a supply can provide?

This is going to be one of the most important factors when it comes to choosing your best power supply. A desktop with a custom pure cooling loop, a high-end motherboard, and dual GPUs requires a higher wattage computer power supply than a simple system. In particular, you have to work with the hardware, which is perfectly acceptable, but use a PSU wattage calculator or something to determine your various components and power play with. Doing so can provide insight into how many watts you need. 

As a general rule, it’s better to err on the side of higher wattage than to try to meet your needs exactly. If you’ve calculated that your system is going to use 500 watts (a typical number for a straight gaming build), then choosing a PSU with 600 or 650 watts of output might be a good option. Because it will give you some overhead to work with, and also allows for possible future upgrades. In short, always go for a power supply that is capable of delivering more power than what your PC really needs.

Some other factors to consider 

Fan of power supply

The fan is one of the most important parts of a power supply unit as it prevents everything inside from overheating or thermal throttling. There must be some good-quality fans connected with the PSU so it doesn’t overheat and keep operating at its true potential. But if the fans of your older power aren’t working properly, you must find a high-quality, reputable brand that has bearings that can be replaced with the ones that are connected to the power supply. 


A power supply is useless if it won’t connect to and power every component in your computer. This means that it needs all the required connector types. Therefore, you must consider checking all the necessary connectors you need. The first connector to consider is the main connector that powers the motherboard. This connector comes in two configurations, 20-pin and 24-pin. The latter is increasingly popular, and it’s likely that your power supply will provide both options. Just check to make sure.

Next is the processor power connector, which comes in 4-pin and 8-pin versions. As with the main power connector, many modern motherboards have switched to a larger format. Again, make sure your power supply is compatible. The most commonly used power connector is the 4-pin Molex connector. It is used for many components including older HDDs, optical drives, fans, and some other devices. Newer SATA components have their own SATA power connector, and you can also use a Molex to SATA adapter if you run out of one. 


It is important to avoid no-name power supply manufacturers and stick to reputable manufacturers only. Here is a quick list of manufacturers known for quality power supplies: Cooler Master, Silverstone, Thermaltake, Be Quiet!, EVGA, Corsair, Seasonic, and Antec. Of course, this is not an exhaustive list and it is important to note that not every power supply from the manufacturers listed above is a standard unit. Therefore, it is important that once you have a wattage rating, you do your due diligence in researching what quality units are available in your price range.


When shopping for a power supply, you will come across specifications like ”OVP” and ”OCP” from different manufacturers. It’s important to understand what they are and what they do to help you navigate your next PSU purchase. Here is a list of considerations that most modern PSUs include:

OCP – Over Current Protection – Prevents excess current in the PSU. It is designed to cut power when it detects 130% to 150% more current. More useful in multi-rail units. 

OVP/UVP – Under/Over Voltage Protection – Shuts down the unit when the voltage exceeds a certain level. Typically most power supplies have 110% to 130%.

OPP – Over Power Protection – Protects against damage if the power drawn by the power supply exceeds its maximum rated wattage.

SCP – Short Circuit Protection – Cuts off the power supply if the output rail is short-circuited – Prevents fire and damage. However, the impedance required to catch a short circuit needs to exceed a certain threshold. In short, it cannot detect every short circuit.

OTP – Over Temperature Protection – Shuts down the power supply unit if the operating temperature exceeds a certain limit. Temperatures higher than specified can indicate overloading or cooling fan failure, and OTP helps minimize damage. 

BOP – Brown Out Protection – Prevents damage caused by a sudden drop in the input voltage of 10% or more. Sudden voltage drops can be a problem because power supplies will try to deliver rated current for as long as they can.


The power supply is the most important part of the computing system since it converts AC power to DC so the PC components can operate properly. It is very necessary for us to purchase a good-quality power supply since a cheap and non-branded power supply can heavily damage your computer’s components. No doubt, the current tech market situation is quite complex since there are several brands with tens of PSU products. At the same time, there are a bunch of factors that can help you uncover a suitable supply for you. 

This post is all about those factors. We have discussed several necessary steps and factors that can assist you to know how to choose a power supply. You must start by looking up the physical factors of the power supply like form factors, connectors, and cabling so it doesn’t cause any issue in terms of compatibility. After that, ensure to check the PSU’s efficiency, wattage, and protection so it can come up to the expectations. I hope this post will be helpful to you when you go to buy a new power supply and you’ll always enjoy its qualities.

Arslan Ashraf
Arslan Ashraf is a tech enthusiast and an experienced technical writer at GamingDairy. He has been writing all types of guides, tutorials, and tips for gamers, developers, and other people who use computers. His way of writing is quite unique: he starts with testing every single piece of Hardware and does a long list of experiments before writing the actual masterpiece. Well, if you have any queries, ensure to connect with him!