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Power supplies come in a couple of form factors. SFX form factor is prevalent in small form factor builds. SFX power supplies feature tighter dimensions than regular (ATX) power supplies and utilize smaller fans for cooling. Smaller fans lead to less cooling capability. This, combined with less space inside the casing, means SFX power supplies are louder, hotter, and usually have shorter warranty periods on average than ATX units.
The SFX PSU market isn’t as prosperous as the regular PSU market since, you know, Mini-ITX builds aren’t mainstream. But, due to the recent expansion of small form factor builds, there are now SFX models in many different power configurations. Today, we are showing the best SFX power supplies you can buy. Units listed below range from 450W to 850W. You’ll notice there are more in-between models (450W, 550W, etc.) because these are more popular with manufacturers, as is the case with regular PSUs.
As we said in our best 600-650W PSUs and the best 700-750W PSUs lists, 50W more or less isn’t as important as the quality of the PSU. If you have to pick between a less powerful PSU that is of higher quality and a lower quality PSU that offers 50W more, always get the former. We tried to pick one (relatively) affordable and one high-end choice for each tier, but since SFX units are more complicated to manufacture, don’t expect large price differences between the two price brackets. BTW, if you’re interested in SFX power supplies, you could also check out our list of the best Mini-ITX cases. Anyway, let’s begin.
1. FSP Pro 450W SFX: Best budget 450W SFX PSU
The budget SFX PSU bracket features lots of different models, and in it, you can find cheap units that have quality components. 450W and 500W units are great for entry-level to mid-range gaming builds.
If you’re thinking, “who the hell are FSP,” you’re not alone. The brand isn’t known because FSP is an OEM manufacturer making power supplies for brands such as SilverStone, EVGA, Thermaltake, and others. The company also sells PSUs under its own brand. The FSP Pro SFX is their affordable line of SFX PSUs that features affordable prices and the 80 Plus Bronze certificate.
This 450W model should offer enough power for budget gaming builds. The unit’s cooled with an 80mm fan which should lead to less noise and lower temps, especially if your Mini-ITX case features high airflow.
If it doesn’t, maybe you should check out our list of the best airflow PC cases. Anyway, the biggest downside of the FSP Pro 450W SFX is the lack of modularity. Overall, this is a solid budget 450W SFX PSU made for undemanding SFF builds.
2. Corsair SF450 Platinum: Best overall 450W SFX PSU
If you want the highest quality SFX power supplies, check out Corsair’s SF Platinum line. These are the best of the best SFX power supplies. Fully modular and made out of the highest quality components. The entry model delivers 450W, is extremely efficient, and features a 92mm cooling fan.
First of all, the performance is top-notch. Load regulation and ripple suppression are excellent, with the fan activating at about 140W load. The noise is pretty low for an SFX unit, with the maximum being about 35Db(A) at max load. Finally, you get a seven-year warranty period which is great for an SFX power supply.
Overall, the Corsair SF450 Platinum is a fantastic SFX power supply. It sports a premium price, and if you want something a bit cheaper but still great, get the 80 Plus Gold version of this PSU. It has lower efficiency, a tad bit lower performance, but also a noticeably lower price.
3. EVGA SuperNOVA 550 GM: Best budget 550W SFX PSU
The 550-600W range can power enthusiast SFF PCs. Gaming builds featuring mid to high-end CPUs and graphics cards. Here you’ll find two models. The first one is a relatively affordable unit that still packs quality components, and the second is the ultimate choice in this power bracket.
The EVGA SuperNOVA 550 GM is a pretty good SFX PSU. It bears the 80 Plus Gold certificate, and its efficiency is in line with the stamp. Its 650W cousin has excellent performance and relatively low noise, so we presume the same can be said about the 550W model.
Load regulation and ripple suppression results are pretty good, and working temps are in safe ranges, even when testing in a hot environment. The PSU features a fully modular design and comes with a bunch of cables, enough for any GPU no matter how power hungry it is. And despite its affordable price point, you get a generous seven-year warranty period.
Overall, this is an excellent SFX power supply for the money that offers enough power for almost any small form factor build. If you want a reliable power supply that sells for a two-digit price point (under normal market conditions), this is the one to get.
4. Corsair SF600 Platinum: Best 550-600W SFX PSU on the market
The SF600 Platinum is the best SFX power supply in the 550-600W tier, period. There’s no better choice than this one. Yes, it’s expensive (about 50 to 60 percent higher than the SuperNOVA 550 GM), but it delivers the best performance in the class.
It’s also relatively silent and has top-notch efficiency. Measurements such as load regulation and ripple suppression are also best in class. A fully modular design is the standard at this price point, and you also get a seven-year warranty. Finally, there’s the SF600 Gold version on the market that sells for noticeably less.
5. Seasonic SGX-650: Best 650W SFX-L PSU
Now we enter the realm of high-end SFX power supplies that pack enough power for high-end gaming systems. There’s no budget option here because there simply aren’t budget SFX units in this power tier. Managing to cram so much power inside this small case is an expensive endeavor.
Seasonic’s Focus Gold is a mid-range PSU line that has great performance for the money, and this SFX version is no different. The Seasonic SGX-650 is a fully modular unit that has excellent performance. It’s fairly quiet even when under heavy load inside a hot environment. It has excellent efficiency, in line with the 80 Plus Gold certification. You get a ten-year warranty, three years longer than most other power supplies featured on this list.
Low noise and excellent working temperatures are achieved by using a 120mm fan meaning this is an SFX-L unit. That means this power supply is a bit deeper than standard SFX units, measuring 125 x 125 x 63.5 mm. You can still fit it inside most Mini-ITX cases but not all, so make sure to check for compatibility before pulling the trigger.
6. EVGA SuperNOVA 650 GM: Best 650W SFX PSU
If your case cannot fit an SFX-L power supply, get the SuperNOVA 650 GM from EVGA. It’s a bit cheaper than the Focus Gold SGX-650. It also has a standard 100mm depth instead of the 125mm found on the SeaSonic model.
Performance and efficiency are in line with the SeaSonic model. In other words, they are pretty damn good. Load regulation isn’t worthy of getting a medal, but it’s more than decent. We can say the same about ripple suppression. Not the best in class but more than decent.
When it comes to the noise, this one is quieter than the Corsair SF600, especially under heavy load. The semi-passive mode is here, like with most other models featured on this list. It works until the load goes north of 120W, after which the fan turns on.
The PSU comes with a seven-year warranty, which is excellent and in line with other high-end models. Overall, this is a very good power supply that offers plenty of power in a small package, and that’ll be enough for the most demanding SFF builds.
7. SilverStone NJ450-SXL: Best passive high-end SFX PSU
If you want to build a silent small factor build and want a passive SFX power supply, there’s only one model that fits the bill. It’s the NJ450-SXL from SilverStone. If you need recommendations for a quiet PC case, our list of the best quiet PC cases includes a number of whisper-quiet enclosures.
Anyway, the NJ450-SXL is a fully modular model that looks pretty nice. The black aluminum heatsinks covering the whole body are slick as hell. It’s a shame this power supply won’t be visible in most of the builds.
This is an SFX-L unit, measuring 125 x 130 x 63.5 mm. Bear in mind that this model won’t fit into every small form factor case. It’s also pretty heavy, heavier than every other SFX power supply. Altogether, this model gives up a monolithic feeling of pure power.
Since there’s no cooling fan, there’s zero noise. If left working inside a hot (over 40 degrees Celsius) environment, the PSU won’t be able to reach 100 percent load. a working environment that hot combined with a prolonged heavy load could also lead to the PSU shutting down after a while.
But if it’s used in a system that has a temperature lower than 40 degrees Celsius, this power supply is impressive. Efficiency is in line with the 80 Plus Platinum certificate found on the front of the PSU. Working temperature doesn’t go over 42 degrees Celsius when under 100 percent load.
Load regulation and ripple suppression are excellent. A three-year warranty period isn’t a good omen, but if you want zero noise in a small form factor PSU, this is the sole choice. The price is about the same as the Corsair SF750. In other words, if you want a silent PC in a small case, get ready to pay a premium.
8. Corsair SF750 Platinum: Best overall SFX PSU
Placing 750W of power inside the SFX housing is a feat in itself. If you need so much power for a small form factor build, it isn’t likely you’ll cut corners. So, in this category, we only have one model. The best of the best.
The Corsair SF750 Platinum is the best 750W SFX power supply money can buy. The SF750 Platinum is a top-notch product made from premium components that excel in every category. Efficiency and performance are brilliant. Load regulation is tight, just a tiny bit worse than on the SF600. Ripple suppression is excellent, the best among SFX power supplies.
The semi-passive mode works until 300W load, which is impressive for an SFX unit. After the fan starts spinning, the noise can reach 40Db(A), but only if you manage to achieve maximum load (750W). Under medium load, this power supply won’t go over 30Db(A). A seven-year warranty is a standard with the SF series.
Yes, the price is noticeably higher than any other power supply on this list, but if you want the best, there’s a certain price to pay.
9. Cooler Master V850 SFX Gold: Most powerful SFX power supply on the market
Until recently, there weren’t any SFX 850-watt power supplies (we don’t count SFX-L units), and at the moment, we have two. The first is the Cooler Master V850 SFX Gold, and the second one is the EVGA 850 GM. They’re both true SFX power supplies, not SFX-L, meaning they will fit inside any ITX case. Out of the two, the Cooler Master PSU is noticeably cheaper, while they both have the 80+ Gold certificate.
In tests, the V850 proved to be a quality power supply with excellent efficiency and overall performance, especially considering its minuscule size. It’s a bit louder than the competition, but that’s expected considering the impressive wattage. The good news is that the fan won’t turn on until you about 15% load, meaning that the V850 should stay quiet when browsing the web or watching videos.
Further, the PSU has excellent build quality and uses high-quality components, which should give it a long lifetime that won’t end abruptly and with casualties other than the PSU. Do note that early batches of the V850 suffered from an extremely loud fan, but this issue has been resolved in the meantime.
The units that are currently on shells should be issue-free. Also, the supplied cables are on the short side. Not an issue with most ITX cases, but if your chassis is on the larger side of the ITX spectrum, you might encounter issues when hooking up components to the PSU.
SFX power supply specs
Dimensions-wise SFX power supplies measure 125 x 100 x 63.5 mm (width x depth x height) and usually come with a 60mm fan. Some units feature 80mm fans.
If you’re in the market for an SFX power supply, do not forget about SFX-L PSUs. Those are deeper at about 130mm compared to regular, 100mm, depth to accommodate larger cooling fans. Some Mini-ITX cases can fit both SFX and SFX-L power supplies, but it’s best to check whether your case can fit an SFX-L unit before making a purchase.
Also, some SFX models come with mounting brackets allowing users to install them inside regular cases. But we wouldn’t do that because SFX models come with shorter cables, which will turn the process of installation inside a mid-tower case into a world of pain.
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