How Big of a Power Supply Do I Need? – What Rating?

Choosing the right power supply (PSU) can be a scary task. Not to mention you have to consider how big of a power supply you will actually be needing. This can be quite the task for many individuals that may leave you stumped. It is very important to compare different units and models depending on your needs. Doing this in advance will help alleviate any potential problems.

While it may be tempting to just go out and purchase any typical power supply, that is not a smart choice. If you select a PSU that does not offer your computer ample, clean, and reliable power you can run into several problems.

Components That Rely on the Power Supply

Just about every component that is put in your PC will rely on the power supply. Not to mention any external devices that will be plugged into your PC. This might sound quite obvious but it is surprising how many people forget this. In essence, it can be said that your PSU is your PC’s heart, it is what keeps it alive.

What Components Are Going Into the Computer?

Before deciding how big of a power supply you need, identify the other components going into your PC build. First, we recommend that you make a list of the other PC components you plan on purchasing. Each component will be drawing power from your power supply so it is important to understand how much each one will be utilizing.

After you have identified the components that are in your build. You can head over to a simple calculator to identify how much power each component relies on. Cooler Master and Newegg have fantastic calculators that are very simple to use. With the calculator tools, all you have to do is input your PC specs and it will tell you exactly what you will need.

Leaving Room for Future Upgrades

Once you have identified a general recommendation as to how much power your computer is going to consume. It is time to consider whether or not you will be planning on upgrading components in the future. Typically, when you upgrade a computer part you can expect that it is going to consume more power. This is not always the case but I can tell you that as a general rule of thumb, it is to be expected. So, ask yourself this, will I ever want or need to upgrade any of my PC parts?

Gaming computer being upgraded


Now if the answer to that question is no, I would still advise purchasing a larger power supply regardless. The price difference between a 600W PSU and a 700W PSU is quite small. Even if you do not plan to upgrade any parts, you are adding a level of reassurance. Not to mention, if you purchase a reliable PSU it will last you for years. You could potentially use the same unit if it permits on your next PC build.

With technological advancements coming out every day, I typically always say to future proof your computer. Software, game, and applications are requiring more and more from our devices every day. The next thing we know, it is going to be recommended to have a 1000W power supply. I am kidding of course, but you get the point I am trying to get across. To recap, if the price difference is slim, go for the bigger power supply always. 

Power Supply Ratings – What Do They Mean?

When your power supply draws energy it is converting AC power from the outlet and converting it into DC power. This is a general description of how your PC receives the power it requires for the components. With that being said the PSU will have an efficiency rating, this will be in the form of a grade on the box and the unit itself. I am sure you have seen it before it may say something along the lines of “80 PLUS” or just “80+”. This might be confusing, but I promise it is not. It is all about the efficiency in which the PSU delivers the power.

To help explain this a little bit better I will use an example of a 200W power supply. If your PC is requiring 100W of power your power supply will draw 120W of power. Now you may be asking yourself this “If my PC only needs 100W of power, where does the other 20W go?”. The extra power that the PSU draws will be converted into waste. The waste can be potentially harmful to your PC, typically this waste is converted into heat or field waste. Heat waste from your PSU can of course increase the overall temp of your pc. Whereas field waste (excess electricity) can cause damage to other sensitive components.

We have made a chart below for the efficiency requirements for each rating. This chart will give you an idea of how each rating will perform under corresponding loads. 

Rating10% Load20% Load50% Load100% Load
80+80%80%80%
80+ Bronze82%85%82%
80+ Silver85%88%85%
80+ Gold87%90%87%
80+ Platinum90%92%89%
80+ Titanium90%92%94%90%

Modular, Semi-Modular, or Non-Modular Power Supply?

Power supplies come with the ability to be modular, semi-modular, and non-modular. All of them will perform the exact same function but it comes down to cable management. Depending on what option you decide will affect not only the look of your PC but the airflow within the unit as well.

Non-Modular Power Supplies

A non-modular PSU will come with all of the cables already attached to it. This can be a positive aspect as you do not have to worry about too much hassle. You also will not have to worry about missing any cables as they will be attached to the power supply. However, they will make cable management a very unenjoyable experience. Since the cables are attached to the unit you cant unplug the unused cables. The excess of cables in your PC build can leave it looking cluttered and messy. Not to mention, it can significant hinder the airflow within your PC causing it to run hotter than expected.

Messy power supply cables

Semi-Modular Power Supply

A semi-modular power supply is just as it sounds. It will come with only the essential cables attached to the unit. The cables that come attached will usually be a 24Pin ATX, 1 PCIe, 8Pin for your CPU, and a SATA cable. Additionally, there will also be cables included with the power supply that can be fully detached. The nice thing about a semi-modular power supply is the cable management and cost compared to a full modular supply. I like to think of it as a happy medium, you are getting the best of both worlds. You are getting a little bit of the benefits from the non-modular and modular power supply.

Modular Power Supply

As I am sure you know by now; a fully modular power supply comes with no cables attached. This is typically the most expensive option for a power supply. With that being said, it does offer you significantly more options for cable management and customizability. If you are looking to have full control over where the cables go, how many are attached, and how they look. This is the option for you. You are also able to order custom colored cables for the unit if you are trying to achieve a theme for your build. Of the three options, a fully modular power supply will offer you the most versatility but at a higher price.

Final Thoughts

All in all, I recommend that you put just as much effort into the power supply selection in comparison to any other component. There are many options and grades available that can make a significant difference to your pc build. You also want to select a power supply that is big enough to handle your requirements not only now but, in the future as well.