What Is An SFX Power Supply? The Small Form Factor Of PSUs!

In the world of computer hardware, there are a lot of acronyms. Some are easy to understand and others, like the SFX power supply, might be a bit confusing. What is an SFX power supply? Does your computer need it?

SFX (small form factor) power supplies are perfect for your home or office computer. They provide all the features you need to build a powerful personal computer in a small form factor, such as compact size, whisper quiet operation, and modular design that reduces clutter inside your case. The PSUs with SFX form factor allow you to pack more power into less space than other power supplies available on the market today.

What Is An SFX Power Supply?

SFX is a power supply form factor. It’s smaller than ATX, and they’re designed to fit in smaller cases. As you might have guessed, SFX was introduced by SilverStone in 2003 as an alternative to the larger ATX standard that had been around since 1996. SFX units also tend to be quieter than other models because they use a high-quality fan that’s optimized for low noise levels. They are typically 80 or 90mm wide and 150mm tall. They’re usually around 30% quieter than ATX power supplies, and their smaller size allows you to build a system in a smaller case or gain benefits like better airflow and more silent operation.

Features Of An SFX Power Supply

The SFX power supply features a small form factor and a low-profile design. It’s an internal power supply that you can install without needing to remove your motherboard or add extra cables.

These units mostly have a single rail, meaning they deliver power from a single 12V rail rather than multiple rails, as some higher-end ATX supply models do. This also means just one of your case’s internal cable connectors needs to provide +12V power; unused ones can be left unconnected and hanging out of sight below the motherboard (which is excellent for keeping things tidy).

In addition, many SFX PSUs come with only one +12V output; if you want more than two graphics cards in SLI/CrossFire mode, you’ll need something with dual outputs here, too, though.

Advantages Of An SFX Power Supply

Why would you want an SFX power supply? Well, there are several advantages that make them a good choice for your small form factor (SFF) build.

First of all, they’re quiet and lightweight. Unlike ATX power supplies which are typically large and heavy with multiple fans, SFX models are smaller and use fewer moving parts to operate. This allows them to work more efficiently while producing less noise than their larger counterparts. That’s good news if you’re looking to build an ITX PC or something even smaller like an HTPC (Home Theater PC).

Second — and this is important — SFX PSUs are available in a wide range of output levels with maximum being 800W as of now. This means that If you need more power for something more demanding than a graphics card or two or you are trying to build a 4K Gaming PC, then there’s no problem in choosing SFF/SFX PSUs.

Disadvantages Of An SFX Power Supply

You should be aware of some disadvantages of an SFX power supply: one, they are more expensive than ATX power supplies. This is because they offer fewer wattage options, and the parts inside are smaller and have to be built with more precision.

Two, they aren’t modular, so you can’t swap out your own cables. This means if you want to use a different length or color cable on your computer, you’ll need to get a whole new item from the manufacturer instead of just swapping in your own parts (though there are exceptions).

Lastly, they aren’t upgradeable like ATX power supplies can be — you have to buy a brand-new one if you need more wattage later on down the road (unless you buy something with an external housing). If this happens while shipping costs are low enough, it might turn out cheaper than buying two separate items initially — but don’t forget about those other considerations mentioned above.

Average Price Of An SFX Power Supply

The average price of a good and quality SFX power supply is around $100-$150, which is much more than the ATX-style cases. In general, you can expect to pay a premium for trustworthy designs that are more efficient and/or have higher wattage. Also, some SFX PSUs are modular, but you must pay the price for the convenience. 

If you’re looking to save money but still want high quality, it may be better to skip the modular version and go with the non-modular. While this means that your cable management will not be as clean as it would be in a modular design, it will also mean that you won’t have to pay extra for something you don’t need or want.

Frequently Asked Questions

Wrap Up

We hope this article has helped you better understand SFX power supplies and which one is suitable for your PC build. If you have any questions about using an SFX PSU in a specific case, please let us know in the comments below! We’re here to help.

Now that you know what SFX power supplies are and why they’re so useful, hopefully, you’ll start seeing them more often. They’re great for any computer that needs a little extra juice in terms of power but doesn’t have room for a full-size ATX PSU. If you have any questions about SFX PSUs, just let us know in the comments below!

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Anna Bonilla
Anna Bonilla

Anna isn't just any ordinary Computer Hardware Expert, she's highly skilled and multi-talented. She's a graphic designer, a writer, and a social media expert. At ErrorBook, she helps her readers in understanding the purpose of different hardware components and also helps pick the best PC Parts for their money. She also loves babysitting her nephews, baking, and crafting coffee.

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