Good things do come in small packages, such as Lian Li's new SX lineup of high-power fully modular ATX power supply units. Available in 1200W (SX1200P), 1000W (SX1000P) and 850W (SX850P) variants, these ATX 3.1 PSUs come in a chassis that measures in at just 140mm in depth, and feature 80 PLUS Platinum certification.

On 13th November 2025, Lian Li unveiled its new SX line-up of high-power compact power supply units (PSUs). Featuring 80 PLUS Platinum certification and compliance with the ATX 3.1 standard, the SX line-up is available in black or white colourways, and comes equipped with a native 12V-2x6 power connector for next-generation graphics cards and multiple 8-pin PCIe power connectors for added flexibility in terms of the components that you can use in your PC build with this PSU. Equipped with a smart cooling system where the PSU's 120mm cooling fan only activates when the PSU is above 40% load, the key selling point for the SX lineup's got to be its compact size, where it measures in with a depth of just 140mm.

Available in 1200W (SX1200P), 1000W (SX1000P) and 850W (SX850P) variants, we'll be taking a closer look at the range-topping SX1200P variant for this article - read on to learn more about the SX1200P and its features, and to see it as part of a demo build featuring Lian Li's new LANCOOL 217 INF PC case (that I've also reviewed here), HydroShift II LCD-S 360 TL AIO CPU cooler and a bunch of Uni Fan SL-Inf Wireless case fans!

Packaging

The PSU comes shipped in a rectangular box with Lian Li’s signature black and blue colourway, with information on the specs of the PSU peppered on all sides of the box.

In terms of accessories, Lian Li's included the following with the SX1200P:

• Thank you card
• User's manual
• Pack of cable ties
• Power cord
• Drawstring bag containing PSU modular cables

Aesthetics & Physical Features

The first impression that I get from handling the SX1200P, it’s pretty compact for a 1200W PSU that’s 80 PLUS Platinum certified, where given that it has a depth of just 140mm, it should fit very easily in most PC cases with no issues at all. In case you’re wondering about its exact dimensions, the SX1200P and in fact, the rest of the SX line-up, measures in at 150mm (W) x 86mm (H) x 140mm (D).

In terms of aesthetics, the SX1200P has a pretty run-of-the-mill appearance for a power supply unit, where we get your usual power cable connector and ventilation openings on the front of the PSU. You’ll notice that it comes with an on/off switch right next to the power switch - this switch is used to enable or disable the PSU’s fan-less operation mode, I’ll talk more about this feature later on in this article. Moving over on the rear of the PSU, we get your usual connectors for the various modular cables that the SX1200P comes with.

On the left side of the PSU, we get the Lian Li logo and model of PSU printed on, nothing too fancy here, and on the right of the PSU, detailed specs of the SX1200P along with the usual safety warnings and such.

We don’t get anything of note on the top panel of the PSU, and over on the bottom panel, we catch a glimpse of the 120mm fluid dynamic bearing (FDB) cooling fan through an embossed mesh panel that has some interesting geometric effects for added visual interest, all topped off by a plastic Lian Li badge in one of the four corners.

The PSU's modular cables come packaged in a nice cloth bag, where we do get some minor variations in terms of what cables come included with the SX line-up, as per the chart that you can see above, which also has the respective lengths of the cables that come included with the PSU.

Of note is the 12V-2x6 power cable that Lian Li's included with the SX lineup of PSUs, where the said cable features a dual-coloured in-house custom moulded 12V-2x6 connector. Given how infamous this connector design is with countless stories of melted connectors when improperly inserted into the corresponding power connectors of power-hungry graphics cards powered by GPUs such as the RTX 5090 and RTX 4090, Lian Li's in-house design doesn't disappoint, where it feels very sturdily built. As far as I could tell, there wasn't any wiggle room for the pins embedded within the housing of the 12V-2x6 connector, which should go a long way in helping to ensure good electrical contact when hooked up to your graphics card.

Of note is the connector's dual-colour design, where the blue part of the connector will fully disappear if the connector is properly inserted into the 12VHPWR connector on your graphics card. If it’s improperly inserted, you’ll be able to see a tinge of blue, which serves as a warning that the connector is not properly seated.

On that note, it’s great to see that with the SX1200P (and the SX1000P), we get a 12V-2x6 cable that terminates in two 8-pin PCIe power connectors, which gives end-users a lot of flexibility in terms of how to run the respective power cables to your graphics card, be it one that uses the 12V-2x6 power connector or one that uses the traditional 8-pin PCIe power connector(s). We do also get three vanilla 8-pin PCIe power cables with the SX1200P (and the SX1000P) – plenty of power cables to go around for your devices. The SX850P, being the bottom 0f the pack, doesn't come with the aforementioned 12V-2x6 to dual 8-pin PCIe power cable.

Another point to note, the main PSU cables feature a flexible braided design that helps make cable management more effortless, where we also get cable combs for some of the modular cables to further help things along from an aesthetics and tidiness perspective.

Again, not all the modular cables come with the said braided design - the accessory cables, such as the SATA power cables and the 12V-2x6 to dual 8-pin PCIe cables come with flat ribbon sleeving instead.

Specifications

Official Lian Li product page: https://lian-li.com/product/sx-platinum/

Let’s run through the specs of the SX lineup of power supplies real quick. We get three power options to choose from, 850W, 1000W and 1200W, which is the model that I have here in this video. The PSU is really compact in size, where it has a depth of just 140mm, making it really suitable for PC builds where space is an issue. The SX line-up is ATX 3.1 compliant, conforms to the 80 PLUS Platinum standard in terms of efficiency, and features a 120mm fluid dynamic bearing fan for cooling, where it comes with a silent operation mode that I’ll talk about shortly.

For peace of mind, the SX lineup comes with a 10 year warranty, and if we were to pop over to PPLP’s website, a certifying body for PC hardware components such as PSUs, they’ve given the SX1200P in particular a "Platinum" rating, where this PSU’s also received a "S" rating in terms of noise levels under Medium and Heavy loads, which is reassuring to see.

One feature that Lian Li touts with the SX lineup is the fact that they come with a smart cooling feature that switches off the cooling fan when the PSU is at or under 40% load, which helps reduce noise levels and extends the lifespan of the cooling fan. End-users have the choice of enabling or disabling this feature by flipping the switch pictured above – when the switch is set to "Off", this means that the smart fan mode will be active, and the fan will only kick in at PSU loads above 40%. When the switch is set to "On", this disables the smart fan mode, and the fan will run as long as your PC is powered on.

Rounding off this section on PSU specs, it does seem like the SX line-up of PSUs (or at least the SX1200P in particular) is very likely based off an OEM design from a Chinese company called Zhong Yuan Power, as per the little line highlighted above on the side of the PSU. Just a little tidbit of information in case you’re wondering who the OEM is for this PSU!

Build Experience

The experience of using the SX1200P as part of a PC build was as smooth as it could get, where I used it alongside a bunch of Lian Li components, namely the LANCOOL 217 INF PC case, HydroShift II LCD-S 360 TL AIO CPU cooler and three Uni Fan SL-Inf Wireless reverse blade case fans. The motherboard and graphics card in this build were a Gigabyte X670E AORUS MASTER and Gigabyte AORUS GeForce RTX 4090 MASTER 24G respectively.

Installing the SX1200P inside of the LANCOOL 217 INF was pretty straightforward, owing to the fact that the SX1200P has pretty compact dimensions.

The LANCOOL 217 INF has two mounting positions for the PSU, and as can be seen, I have the SX1200P mounted in the sideways position.

Getting the cables to where they needed to go was pretty easy too, and the cable combs really do help in making the cables look just that little bit neater, which is always appreciated.

Demo Build Aesthetics

Conclusion & Pricing

To sum up, the Lian Li SX1200P power supply unit seems to be a pretty capable PSU with numerous pluses going for it, the main selling point being that you get lots of quality in a compact package that measures in at just 140mm in depth. The quality of the included braided modular cables is great, and I really like how Lian Li’s included a 12V-2x6 power cable that terminates in dual 8-pin PCIe power connectors so that you can use this PSU easily with say, a high-end AMD Radeon graphics card that utilises the traditional 8-pin PCIe power connector, while still having plenty of other 8-pin PCIe power cables for other devices,

In terms of pricing, the SX1200P is available for a MSRP of US$159.99, while the SX1000P variant goes for US$149.99. The SX850P, which is the 850W variant, can be purchased for US$119.99.

Get this PSU from Amazon: https://amzn.to/49YAaXV (affiliate link)

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The PSU, PC case, AIO CPU cooler and case fans featured in this article were media samples provided by Lian Li.