SFX power supplies are made for small form factor builds. They feature more compact 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.
Today, you can find SFX PSU models with power delivery up to 800W. Cooler Master announced their upcoming SFX Gold series that includes an 850W unit back in January but due to the current situation, it’s unknown when they will launch.
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.
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 8 models ranging from 450W to 750W. 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 600-650W and 700-750W PSU pieces, 50W more or less isn’t as important as is 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. Let’s begin.
Best SFX PSUs – Our Picks
|Award||Power Supply Unit|
|Best Budget 450-500W SFX PSU||FSP Pro 450W SFX|
|Best 450-500W SFF PSU||Corsair SF450 Platinum|
|Best Budget 550-600W SFX PSU||EVGA SuperNOVA 550 GM|
|Best 550-600W SFX PSU On The Market||Corsair SF600 Platinum|
|Best 650-700W SFX PSU||SeaSonic Focus Gold SGX-650 SFX|
|Best 650-700W SFX PSU Alternative||EVGA SuperNOVA 650 GM|
|Best 750W SFX PSU On The Market||Corsair SF750 Platinum|
|Best 700W Passive PSU||SilverStone SST-NJ450-SXL|
Best 450-500W SFX PSUs
This power 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 mid-range builds featuring up to 6-core CPUs, and mid-range graphics cards. Something like an older Core i7 (7700K for instance) or the Ryzen 5 3600 combined with up to RTX 2060.
Best Budget 450-500W SFX PSU
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 mid-range 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. This isn’t a modular power supply and it doesn’t have any detachable cables. Overall, this is a solid budget 450W SFX PSU made for undemanding SFF builds.
Best 450-500W SFF PSU
If you want the best SFX power supplies, check out Corsair’s SF Platinum line. These are best of the best SFX power supplies. Fully modular, and made out of 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 noticeably lower price.
Best 550-600W SFX PSUs
This is the range made for powerful builds. Builds featuring CPUs such as the Ryzen 5 3600 or Ryzen 7 3700X, or the Core i7 9700K and graphics cards up to RTX 2070 Super. We picked 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.
Best Budget 550-600W SFX PSU
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 (under normal market conditions), this is the one to get.
Best 550-600W SFX PSU On The Market
The SF600 Platinum is the best SFX power supply in the 550-600W tier. 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. Fully modular design is a standard and you also get a seven-year warranty. Finally, there’s the SF600 Gold version on the market that sells for noticeably less. It offers virtually the same performance but is noticeably noisier and has lower efficiency.
Best 650-700W SFX PSUs
Now we enter the realm of high-end SFX power supplies that pack enough power to run high-end gaming systems. Think something like the Ryzen 9 3900X or 3950X, Core i9-9900K, or the newly released i7-10700K coupled with the RTX 2080 Super.
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. You won’t find SFX PSUs with two-digit prices in this power bracket. And if you happen to find one skip it except if it’s on a discount.
Best 650-700W SFX PSU
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 stamp. 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 at 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.
Best 650-700W SFX PSU Alternative
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 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 over 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.
Best 750W SFX PSU
Placing 750W of power inside the SFX housing is a feat on 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.
Best 750W SFX PSU On The Market
This is the best 750W SFX power supply money can buy. The SF 750 Platinum is a top-notch product made from premium components that excels 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, best among SFX power supplies.
The semi-passive mode works until 300W load, which is impressive for an SFX unit. After the fan turns on 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). Seven-year warranty is the 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.
Best Passive 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 Nightjar NJ450-SXL from SilverStone. This 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 at 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. It’ll also shut down at random 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. 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 with the Corsair SF750. In other words, if you want a silent PC in a small case, get ready to pay a premium.