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Corsair SF850L review – unhindered small form factor power

Small but powerful, we find what the SF850L PSU has to offer
Last Updated on May 1, 2024
Corsair SF850L review
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When it comes to building out a small form factor, there are plenty of special considerations and components you have to look for. That includes an SFX PSU, a more compact unit for mini-ITX cases or similar, and so we see how they compare with the rest, as we review the Corsair SF850L. What might be a strong choice for compact builders usually comes with its own niche tax, but this power supply might just change that.

  • Corsair SF850L fan, source PCGuide
  • Corsair SF850L logo side, source PCGuide
  • Corsair SF850L logo profile, source PCGuide
  • Corsair SF850L back side logo, source PCGuide
  • Corsair SF850L info label, source PCGuide
  • Corsair SF850L cable connectors side, source PCGuide
4.5 /5
Editor’s Rating
How We Review
  • Wattage: 850W
  • Form Factor: SFX-L
  • Rating: 80 Plus Gold, Cybenetics Platinum
  • Design: Fully modular
What We Think

The Corsair SF850L doesn’t drop much even as a small factor choice. Keeping costs similar to those of ATX supplies means you’re not paying over the top for it. Along with that, you get many years out of it, with a 7-year warranty but also with an ATX 3.0 and PCIe 5 native connection, you can get many years out of it.


Primarily the Corsair SF850L offers a smaller size, but being a strong power supply it has a strong offering without cutting out much. As the PSU is just a shrunken-down option it still is mostly the same as the standard ATX options, and unlike the RM1000X Shift we reviewed, the power connectors are on the usual end. It utilizes Type 5 cables, in case you want to swap them out, but provides a good range of cables and connectors by standard.

That includes being ATX 3.0 and PCIe 5 compatible, giving you the 12VHPWR connector out of the box and without faffing around with any adapters that haven’t had the best reputation since it’s included with RTX 40 series graphics cards. Along with a good range of connectors, the actual sockets are well spaced out, not bunched up right next to each other means it’s a lot more accessible and easy to plug in and out the connectors. Although stacked on top, it requires some space to unclip each which might get in the way.

The Corsair SF850L doesn’t drop much even as a small factor choice

Otherwise, you get a simple-looking logo on the side and a model name with standard Corsair branding. On the other, you get the full specs and safety information of the unit and an essential warning about not opening it up. To note there is a hybrid choice, and you don’t get control of the fan on board, which is a 120mm fluid dynamic bearing option providing it with a strong cooling choice.


SF850L is an ideal choice for small form factor PCs with its SFX-L design. Measuring 125 x 63.5 x 130mm it does suit those mini builds but even then offers up an adapter if you want to use it in a bigger case, not that we would recommend doing so as it can stand out a bit.

With the micro fit cables and full modularity, it does offer a useful addition to many small builds, including cable management. In that small space, we see the fan take up most of the space on the intake. This should still be adequate for the cooling as the compact internals are likely to reach higher temps with the 850W rating and so might need some work so let’s see how it fairs.

Sound and efficiency

Rather more importantly the performance of the PSU is key as well, and the SF850L does well in general to achieve a strong result. Although 80 Plus gives it just the gold standard, Cybenetics tests put it at a Platinum efficiency. At 115V the average efficiency archives 90.577% with the 5VSB efficiency at 83.657%. With the 230V version at an average of 92.33% and 83.020% for the 5VSB rail.

As for the sound of the PSU, it only achieves a Standard+ rating, as it averages 36.09dB(A) for the 115V, and a bit less at 230V with 35.92sB(A). That does leave it on the louder side of choices, but that is to be expected with the work it has to do to keep temps under wraps in such a small unit. Even then it’s unlikely to be heard when you’re engrossed in heavy tasks and there are other components taking the spotlight.

What GPUs to pair with the PSU

There’s not really much you miss out on with this 850W PSU, although if you’re going for an SFX PSU, then you’re likely in a small build. This means you’re going to want to get an ITX GPU or low-profile graphics card that can also actually fit into a narrow space.

You can easily power even the likes of the RTX 4080 Super and RX 7900 XTX, as they are easily powered by the 850W. With only a TBP of 320W and 355W respectively. However, depending on your case and space, it might not be feasible to fit those in with their large cooling solutions, and instead looking down towards an RTX 4070 Super or RX 7800 XT might be more reasonable.

Corsair SF850L is a handy dandy little PSU

Warranty and support

The SF series of Corsair power supplies has a tad bit shorter warranty period than its longest option of 10 years as seen in the longest ranges. But it’s still on 7 years of warranty and support for the unit since purchase. Providing you a length period of knowing you are going to be covered and how long it might last you. As it is a strong choice for your next build, no need to spend any more just re-use and that is a key consideration for the long term. Especially with the long-term features on it.


The Corsair SF850L is a handy dandy little PSU. As a small form factor choice, it provides great power and performance with great efficiency at the cost of some sound drawbacks. However, it costs as any standard ATX choice and does not come with any tax for being more unique. Whilst also providing a strong future-proof choice considering the native ATX 3 support available that will give you many years of changes and upgrades.

With a fascination for technology and games, Seb is a tech writer with a focus on hardware and deals. He is also the primary tester and reviewer at BGFG and PCGuide.