Atx sfx: ATX vs. SFX: Which power supply (PSU) standard is best for your PC?

ATX vs. SFX: Which power supply (PSU) standard is best for your PC?

FSP Dagger Pro 850W
(Image credit: Rich Edmonds / Windows Central)

ATX vs. SFX: Which power supply (PSU) standard is best for your PC?

Best answer: Unless you specifically need a smaller SFX power supply because you’re building a small form factor PC, you will find much more choice with ATX in both hardware and price.

ATX vs. SFX: It’s all in the size

The important point to remember is that these two terms relate to a size of power supply, not a spec. One isn’t necessarily better than the other.

And that’s physical size, too, not capacity. SFX power supplies are physically smaller units than ATX power supplies, and that’s the main reason you’d want one.

An increasing number of small form factor PC cases simply don’t have the space required for a full ATX power supply. That’s where SFX comes in.

ATX is the most likely choice

It’s possible to get confused when considering an ATX power supply if you’re also using a Micro-ATX or Mini-ITX motherboard in your PC. The size of the motherboard will always be described in your case. But ATX power supplies don’t only apply to ATX cases.

In fact, you’re more than likely going to need an ATX power supply. As above, unless your case specifically states that you need an SFX power supply, then you’ll be OK with a normal ATX one.

Upgrading your PC and reusing the SFX power supply

If you need an SFX power supply now but in the future need to upgrade to a bigger PC case, you can re-use it. As the SFX size is smaller than ATX, you’ll have no trouble fitting it in physically.

But, since they occupy very different footprints, you may need an adapter to properly mount an SFX power supply where normally you would use an ATX. It’ll vary on a case-by-case basis, but don’t just assume you’ll have to throw it out.

If you’re in the market for either an ATX or SFX power supply, these are currently our top recommendations for each.

FSP Dagger Pro 850W

FSP makes great power supplies for the likes of EVGA and Cooler Master, but the company’s own branded PSUs are also worth considering. The Dagger Pro 850W is a great choice for a modern SFF PC build.

EVGA SuperNOVA P2 650W

The best power plant for your PC

You’ll find it difficult to find a better value PSU than this EVGA example. It’s rated for 80 Plus Platinum and has enough power for gaming PCs.

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Richard Devine is a Managing Editor at Windows Central with over a decade of experience. A former Project Manager and long-term tech addict, he joined Mobile Nations in 2011 and has been found on Android Central and iMore as well as Windows Central. Currently, you’ll find him steering the site’s coverage of all manner of PC hardware, and you can follow him on Twitter and Instagram.

Can you use an SFX power supply (PSU) inside an ATX PC case?

Be Quiet PSU
(Image credit: Windows Central)

Can you use an SFX power supply (PSU) inside an ATX PC case?

Best answer: Yes. SFX power supplies fit into ATX PC cases but typically need an adapter and possibly extension cables.

What’s unique about an SFX PSU?

Source: Rich Edmonds / Windows Central (Image credit: Source: Rich Edmonds / Windows Central)

If you’re wondering how to fit an SFX PSU in an ATX case, you should know what makes this form factor unique. SFX PSUs are compressed versions of normal power supplies, or ATX PS/2s. An SFX PSU is smaller in size and made to fit into tiny cases. Otherwise, it’s electrically the same. You won’t have to worry about your components not getting enough power.

That said, there can be some differences that could matter depending on how you want to set up your build. The smaller size might open up some breathing room for components, but it can introduce some complications as you try to install it.

How to fit an SFX PSU in an ATX case

Source: NZXT (Image credit: Source: NZXT)

Here’s where things get tricky to explain. How well a SFX PSU fits into an ATX PC case comes down to what the case recommends or supports. Generally it should fit, but you might need an adapter that lets it screw in as a normal PSU would. These aren’t expensive or anything, but they can be a burden to get if you already have your build ready to go. Make sure to check whether your SFX PSU comes with one or not.

Some cases come with this support by default. You’ll have to check what the case can handle. For the most part, if it’s a big ATX case, versus an ITX one, you should be able to fit anything in there. PSUs don’t get bigger than that. If it is indeed a smaller case, it should slot in without an adapter as that is what these types of PSUs are made for. One you have that though, it should perform just as well as any other PSU like the NZXT C650.

The SFX PSU cable problem

Source: Windows Central (Image credit: Source: Windows Central)

One sort of hidden feature with SFX PSUs is that they have shorter cable lengths. This is largely because in small form factor cases, you want everything to be clean and efficient. You don’t want cable nests to stop airflow in an already tight situation. Of course, this is a problem in a big case where your components are spread out.

SFX PSUs will sometimes require cable extensions to properly work inside of an ATX PC case. It’s a minor annoyance, not an expensive one. You might only need extra cable length for a few components, but it’s worth checking before you fully commit to your build. Obviously if you’re building in a smaller case it isn’t an issue. It’s always good to check the dimensions of your case though.

Our pick

Corsair SF Series SF750

A solid SFX PSU for almost any case

This Corsair SF750 is a powerful and reliable modular SFX PSU and is rated 80+ platinum.

Get the best of Windows Central in in your inbox, every day!

Contact me with news and offers from other Future brandsReceive email from us on behalf of our trusted partners or sponsors

Tyler Colp is a freelance writer for Windows Central. He’s written about tech, games, and the culture around them across the internet. Ask him anything about Dark Souls or just follow him on Twitter.

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