Best SFX PSU 2024: Compact power supplies for your small form factor PC

I've built many computers over the years, and picking the best PSU can make or break the experience. Every little bit of space matters for small form factor (SFF) builds, so finding a slim power supply and prioritizing a modular setup is critical. Compared to your average ATX PSU, SFX power supplies are tiny but not necessarily cheaper if you don't search far and wide enough.

Luckily, I've already worked to round up the best SFX PSU to fit your next slim build. They still fit inside most full-tower desktop cases, offering more versatility if you need to power multiple machines with the same unit. Naturally, you'll need to match the total potential wattage on your chosen PSU with whatever components will be inside your new PC, so consider the power draw of each part and pick a suitable equivalent. 

It's always wiser to go a little higher than you need, future-proofing any updates you might not have considered yet. Here are my picks for the best small form factor power supplies, suitable for various budgets and wattage requirements.

How much wattage do I need?

Each component inside your PC draws a certain amount of power from your PSU, and you'll need to provide at least the minimum wattage required to keep things running smoothly. Popular websites like the PCPartPicker builder offer a rough calculation based on the parts you select, but it isn't a guaranteed result. Still, it's better than nothing and should give you an idea of where to start. When in doubt, go 100-150W above your calculated total.

Choosing the best SFX PSU for your compact PC

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Just because they're smaller, it doesn't mean SFX power supplies are necessarily weaker than their full-sized ATX variants. Generally designed for more compact cases, it is possible to mount an SFX PSU with an adapter into an ATX case. Besides their physical size, they do the same job: provide your components power at whatever total wattage they need. It's worth double-checking your case requirements because SFX power supplies are usually only ever selected for the tiniest builds.

Once you've decided which PSU standard is best for your PC, you can choose which is best for you. Our collection of SFX styles is well suited for a small form factor PC, and there are plenty of other size choices when looking for the best power supply in general.

Ben Wilson
Channel Editor

Ben is the channel editor for all things tech-related at Windows Central. That includes PCs, the components inside, and any accessory you can connect to a Windows desktop or Xbox console. Not restricted to one platform, he also has a keen interest in Valve's Steam Deck handheld and the Linux-based operating system inside. Fueling this career with coffee since 2021, you can usually find him behind one screen or another. Find him on Mastodon to ask questions or share opinions.