How to Check Power Supply Wattage: 4 Proven Methods in 2021

It is very important to check power supply wattage on a PC otherwise, you can’t find out how much power a new device will consume after you have upgraded your PC or just built a new system.

Don’t be stingy while buying a power supply. It is one of the vital components of your PC. Without adequate power, the system may not run according to your expectation, or worst-case scenario, it may crash. It will gradually damage the internal component if you continue to use a power supply with lower wattage.

In order to know the required amount of PSU wattage, you need to know how to check it. That is exactly what we are going to discuss in this article. Before you read any further, you need to know –

Why is it important to check power supply wattage?

-“What is the wattage of my power supply?”

It is a natural question when you get a PSU whether it is branded one or it comes with a prebuilt PC. The reasons for checking PSU wattage are many. We have included some of the prominent ones –

  • It is very crucial for gamers to know the wattage of their power supplies as they are used to overclocking.
  • When someone decides to upgrade the entire system by replacing every component except the power supply.
  • When you add an additional and powerful component like a graphics card, aftermarket CPU cooler, casing cooler, hard disk, or RAM.

However, that’s not enough as 2 power supplies of the same wattage and rating can perform differently. Therefore, you may also need to learn about the tier of the power supply. We hope this PSU tier list may help you get an overall idea.

How to check power supply wattage on PC: 4 common yet effective methods

These methods are pretty much common and they work most of the time. Aside from these methods, we will discuss additional topics on the power supply. As a result, you will be left with no confusion or queries regarding PSU and its wattage.

Now, let’s start with the very first method,

1. Find the PSU wattage from its label –

This method is the most common. Generally, it is the first attempt to know the PSU wattage by most people. You can check the PSU wattage from the label that is attached to the PSU. You will see this label as soon as you open the PSU from the box, it can’t be missed.

On the other hand, if you have already installed the power supply in your PC, you will have to remove it from the PSU shroud (if your casing has any) to see this sticker. But before removing, make sure your PC is not connected to any power source and the power supply is turned off.

PSU of & off button

You need to remove 4 screws to take out the power supply from the casing. When you finally have the power supply in your hand, you can see the label indicating the wattage of the PSU.

How to Check Power Supply Wattage: power supply label

2. Check PSU wattage from the manufacturer’s website –

You can follow this method if you have purchased a branded power supply. Local power supplies or the ones that come with the PC case are not branded power supplies. As a result, they don’t contain any information on the internet.

But the case is different with a branded PSU. You can see the details just by visiting the manufacturer’s website. This method is relatively better than the first method as it doesn’t require you to remove the power supply from the case. Also, buyers can get advanced information about the power supply before buying it.

As an example, we have shown the manufacturer’s details of the Cooler Master MWE GOLD 650

How to Check Power Supply Wattage: PSU wattage on the website

Sometimes, prebuilt computers also contain information about the whole component online. But it is possible only when the PC is from a manufacturer.

3. Look at the PSU box to find out its wattage –

Perhaps, this is the easiest among the 4 methods. It is not only the easiest but also will tell the PSU wattage instantly. When you buy a branded power supply, its specification along with all the necessary details will be provided in the box.

You will see the power supply model, rating, specification, whether it is an RGB PSU or not, and everything just by looking at the box. You don’t have to remove the PSU from the case or visit the official website to know the power supply wattage.

How to Check Power Supply Wattage: From PSU box

And that’s not all, you can learn about the power supply wattage by reading the manual that comes with the PSU. Non-branded power supply neither has a box nor a manual. So, it is better to avoid buying a non-branded PSU.

4. Calculate the wattage with a power supply calculator –

This option to check PSU wattage is a rather innovative one. We believe all the major brands of PC components should come up with something like this. Especially, the brands which are involved in selling power supplies should definitely have their dedicated power supply wattage calculator.

A power supply calculator is an online platform that gives a result of the required amount of power a user exactly needs in order to run all the peripherals of his computer smoothly. You may not need the exact result that is suggested by the power supply calculator. Even if you take a lower wattage PSU than the suggested one, you can run your computer well.

Manufacturers try to advertise their products with this type of marketing policy. Although there can be many options, we believe these are the best power supply calculators –

Get to know the power supply sizes –

Aside from the PSU wattage, ratings, and others; it is also important to know what size of power supply will perfectly fit inside your PC case. Yes, that’s right, not all power supplies will fit inside the power supply shroud. You need to be aware of the power supply sizes.

There are usually 3 types of power supplies depending on the size –

ATX and ATX12v power supply

SFX-L power supply

SFX power supply

ATX and ATX12v power supply How to Check Power Supply Wattage: 4 Proven Methods in 2021
SFX L power supply How to Check Power Supply Wattage: 4 Proven Methods in 2021
SFX power supply How to Check Power Supply Wattage: 4 Proven Methods in 2021

Usually has the dimension of 150 x 86 x 140 mm

Usually has the dimension of 130 x 64 x 125 mm

Usually has the dimension of 125 x 63.5 x 100 mm

Fan size: 120-140 mm

Fan size: 120 mm

Fan size: 80-92 mm

Mostly used in gaming and custom PCs

Mostly used in pre-built PCs

Mostly used in mini ITX PC builds

Know about the rating of PSU

Each power supply has a rating marked on it. It indicates 4 terms – Efficiency, Safety, Stability, and Build Material. All these will give an idea about the output that a power supply can deliver to your system.

Let’s take a look at this chart to know about the efficiencies of different 80-Plus PSUs –

80 plus certification tiers

(Source –

Find what people frequently ask about power supply wattage

What are the types of power supplies?

Ans: In general, there are 3 types of power supplies. These were categorized according to time and usage. These are –

  • AT Power Supply – used previously in the old generation PCs
  • ATX Power Supply – still common and can be found in some
  • PC ATX-2 Power Supply – a modern power supply that can be found in modern PCs.

What are the types of power supplies based on cabling?

Ans: Different power supplies can connect differently to other peripherals of your PC. Cabling is a crucial function of the power supply because more and more people are getting concerned about cable management. This is important for those who want to build a gaming or high-end custom PC.

According to cabling, there are 3 types of PSUs –

  • Modular Power Supply – This type of PSU offers the most feasibility of managing cables by minimizing the connections to the motherboard that are only needed. As a result, it can save a lot of space.
  • Semi-Modular Power Supply – This type of PSU features the characteristics of both a modular and non-modular PSU. Unlike the modular PSU, not all connections are detachable. Some cables remain pre-installed but there are options to detach others. This also saves a significant amount of space.
  • Non-Modular or Pre-Installed Power Supply – This type of PSU is just the opposite of a modular PSU. Meaning, none of the cables are detachable. All the cables come pre-installed. Therefore, you don’t get to save much space as the unnecessary cables keep dangling and reduce space by causing clutter.

Why is it important to know the PSU tier?

Ans: Because you can differentiate among power supplies that are of the same wattage and rating. It also organizes power supplies into groups so that you can determine which one is the best.

How to know if I got a bad power supply?

Ans: It is easy. If your computer repeatedly shuts down or loses power, then you may have purchased a bad power supply. You can use another power supply by replacing the defective one to check if the same problem occurs or not. If your computer doesn’t show the same symptoms, then there’s obviously something wrong with your power supply.

Is there a way to test the power supply?

Ans: Yes, there is a simple way to test the power supply. Just follow the steps below –

  • Clear the BIOS first, then clear all overclocking data
  • Keep the battery separated from the BIOS for almost 10 minutes
  • Now, reinstall the battery
  • Then, turn your PC on to check if it runs normally or not.


The power supply is undoubtedly a vital component of your PC. If your computer doesn’t get the required amount of power, the internal component will start to damage and the entire computer will shut down eventually. The loss will be devastating, making you spend a huge amount of money, time, and effort.

So, if you feel like the current power supply isn’t enough to power your computer, don’t waste time and buy a better one immediately. And apply the knowledge and information that you have learned from this article while buying a PSU.

Hi! I am Tanzil, I would like to think of myself as a Tech Nerd. The interest in computers, related parts, accessories, and new technologies have been growing constantly in me. Eventually, the interest became a passion and the passion became a habit. I like to express this habitual knowledge through writing. Therefore, I spend my leisure time writing on computers and technology.