There are many small differences between PC parts, and many of these might not be obvious to the beginner PC builder. One example of this is the PSU (power supply unit). Power supply units come in three different types: fully-modular, semi-modular, and non-modular.

Essentially, you can think of these terms as being hard, medium, and easy for simplification purposes. The modularity of the power supply units refers to the wiring itself; fully and semi-modular units can be customized, while non-modular units are stuck with a built-in set of wires.

Besides their ease of use, there are other benefits and drawbacks of each PSU style that are very important to know. Before building your own PC, you should know the features of each one so you can make the most appropriate choice for your situation.

PSUFully ModularSemi-ModularNon-Modular
CostExpensiveModerately expensiveCheap
Cable ManagementExcellentModerateBad
AirflowWon’t impact airflowMay restrict airflowLikely to limit airflow
Electrical EfficiencyExtremely electrically efficientVery electrically efficientNot electrically efficient
ReusabilityPotential to re-use modular wires in new unitsMay re-use some cablesRemove entire unit for replacement
CustomizabilityPotential for custom cords and color schemesFewer cables are less of an eyesore; can’t customize attached wiresCan’t customize any cables
SizeCompactSemi-compactExtra cables take up excessive space

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    Full Vs. Semi Vs. Non-Modular: What’s The Difference?

    If you’re at all familiar with PSUs, you know that a power supply unit has several wires that connect to different parts of your PC. The PSU brings power from your wall outlet into your PC, then distributes it to the parts that need it.

    However, the way that your PSU delivers this power is what defines it as fully-modular, semi-modular, or non-modular. A non-modular unit, for example, has its wires permanently soldered to the unit. In a semi-modular unit, some of these wires can be removed or altered. In a fully-modular unit, all of the cables can be removed or changed.

    Because of the way these PSUs are made, each has some distinct pros and cons. Non-modular units, for example, are the easiest to manufacture, so they tend to be the cheapest option for PC builders. Similar issues follow the other types, too.

    In the following paragraphs, we’ll go over the differences between these PSUs in even more detail. Read on to learn more!

    Fully-Modular PSUs

    Fully-modular PSUs come with all-modular cables; none are permanently attached to the power supply unit. Because of this, you have the highest degree of flexibility with your build, as well as the most significant degree of cable management. With a fully-modular PSU, you connect only the cables that you need.

    However, fully-modular PSUs are typically only suited to a few niche PC builders. Since most computers will need the cables that a semi-modular PSU provides, a fully-modular unit tends to be overkill. However, there are a few situations where the fully-modular unit will be useful.

    The most common situation for a fully-modular PSU to be useful is when a PC builder wants to choose custom wire colors for their unit. The owner of a fully-modular PSU can choose whichever cables they want (as long as they fit, of course). If a builder, therefore, wants to match wires to their LEDs, they can do so. This may not be an option for a semi-modular or non-modular unit.

    Full Modular Power Supply

    While fully-modular units offer the most customization potential, they also cost the most. Since you will need to buy both the PSU unit itself and any accompanying (custom) cables, you’ll end up with more spent than any other unit. Do you really want to give up that much money on the power supply unit, of all things? Something that most people won’t even see?

    However, for certain PCs, the fully-modular units will still provide an advantage. For an all-glass or mostly-glass chassis, for example, builders usually want to have exceptional cable management since everything will be on display. While some semi-modular units can provide decent cable management, only a fully-modular unit can give you full control over the length, color, and types of cables you attach.

    The same is true for small form-factor or tight builds, where real estate is paramount. Any extra cables left by a semi or non-modular unit can take valuable space from other parts, and they can impede cooling, too.

    Full Modular Psu

    Semi-Modular PSUs

    Semi-modular PSUs strike a midpoint between fully-modular and non-modular PSUs. Semi-modular PSUs typically come with at least the 24-pin connector permanently attached, while your PCIe and 8-pin CPU cables may or may not be connected. Some semi-modular units have modular 8-pin and PCIe connectors, while others don’t. All of the rest of the wires on your semi-modular unit will be modular.

    Semi-modular PSUs offer the best compromise between flexibility and price between modular and non-modular units. Because you have a few cables attached to the unit already, that’s a few fewer cables that the company needs to manufacture separately. This saves you money instantly, at the risk of causing a few cable management issues.

    However, the modular nature of all the other cables on a semi-modular unit still makes it so cable management is usually excellent. You can still attach only the cables you need. It may be more challenging to color-coordinate cables, though, if some are already connected to the PSU. Most PC builders will not be concerned with this, however, as most PSUs are hidden anyway.

    Semi Modular Power Supply

    The price difference between fully-modular units and semi-modular units is not that high initially. However, if you end up buying custom cables for a fully-modular unit, the price quickly skyrockets.

    If you’re looking to use the stock cables that come with your PSU, though, the choice between a fully-modular PSU and a semi-modular one might be difficult. Some users will conclude that they may as well pay a few more dollars for a fully-modular unit, while others will be fine saving those dollars with a semi-modular one. It ends up being mostly personal preference in the end.

    Semi Modular Psu

    Non-Modular PSUs

    As we said earlier, non-modular PSUs are just that: they can’t be altered. All of the cords that the PSU could possibly need are attached to the unit. However, because of this, if you don’t end up using all of these cables, you could end up with extras just hanging around. These extras bother some people, especially if your PC has a lot of windows for display.

    Moreover, these extra cables can cause more than just aesthetic issues. If you have too many cables lying around, they could impede airflow, cause closure problems, and even collect more dust. If your computer case has some functional wire management areas, then you may not need to worry about this, but any case without proper cable management will end up with a “nest” of extra cables.

    Large PCs, in particular, tend to be well-suited to non-modular PSUs. Since these PCs have plenty of space, you can usually spare some of that for extra cable storage. However, it all depends on your chassis.

    Non Modular Power Supply

    If you do have a large PC with extra storage for wires, buying a non-modular PSU is an excellent way to recoup some of the money spent on the case itself, since larger cases tend to be more expensive.

    Non-modular PSUs, in the end, are an excellent option for a beginner user, since all the wires are already in place and attached. A non-modular PSU will be significantly cheaper, too, so it’s a good option for a starter or budget build. However, the extra cables might cause additional problems for a beginner with a small case, too, so it’s a bit of a balancing act.

    Non-modular PSUs are also an excellent option for window-free PC builds. While these builds are much less common nowadays with builders favoring the glass look, it’s an important feature to note anyway. If people can’t see the extra cables anyway, there’s no reason to spend more on a modular unit!

    Non Modular Psu


    In the end, there are pros and cons to each type of power supply unit. Each class has situations where it’s the best option and the worst option. However, the vast majority of users will use either semi-modular or non-modular units, with semi-modular going to more experienced builders and non-modular being favored by budget and entry-level builders.

    While fully-modular units are useful, you can shave a bit of extra money off of your build’s final price by choosing a semi-modular unit. Since a semi-modular PSU has virtually no disadvantages besides being unable to customize the color of your cables, it beats out a fully-modular unit in the majority of scenarios.

    Which PSU unit is your favorite? Have you used mostly one type in the past, or do you pick based on what suits your build best? Let us know in the comments below.

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