Lian Li PE-550 550W SFX Power Supply Review
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Lian Li PE-550 550W SFX Power Supply Review

May 20th, 2017 James Leave a comment Go to comments



We’ve only seen a couple of products from Lian Li here at pcG and both of them have, somewhat predictably been Cases. The first was the excellent PC-X510 while the second was the far more disappointing PC-K5WX. Well this time around it’s not a Case, that’s right Lian Li produce another of the eight core PC components; the part that brings it all to life; the humble Power Supply. But this is no ordinary PSU as the Lian Li PE-550B is actually a SFX Power Supply.

The Lian Li PE-550 550W SFX Power Supply measures in at just (D)130mm x (W)125mm x (H)63.8mm, meaning that it’s significantly smaller than your regular ATX Power Supply. This particular sample features a power output of 550W, but a 750W version is also available. The PE-550 also boasts an efficiency rating of > 86.5% putting it in the Gold Efficiency category. The PSU is equipped with a 120mm fan that produces no noise at low temperature/power states and comes with six cables (24/20-pin power, 8/4-pin power, 8/6 pin (GPU) power, x2 SATA power and x1 Molex/floppy power).


Lian-Li-logo ‘For SFF-lovers the Lian Li PE-750B is a dream come true, the comfort of the SFX-size and all top features that you would expect from high-end ATX power supplies, combined into one product.

The PE-750B power supply uses the compact SFX-L-form factor that eliminates one of the few drawbacks of the traditional SFX format. The result is a powerful SFX-L power supply with an extremely high continuous output of 750 watts and semi-passive fan control which switches on the 120mm fan at around 30% load.’



The Lian Li PE-550 550W Power Supply arrived at pcG in a simple yet smart looking predominately black box proudly highlighting the power supply’s 80-Plus Gold efficiency rating and the fact that it is a SFX size. As you can see from the image above the PE-550 is also ‘Optimized for PC Gamers and PC Enthusiasts’, not sure what that means… 😉



On opening the box we find that the Power Supply and the cables are well packaged and presented. With the PSU itself sealed in a plastic bag and all of the cables neatly stowed in a cloth bag. Sitting in the top of the box we find a simple, yet informative specifications sheet (see Specifications/Features below).



Within the box we find the aforementioned specifications sheet, the Power Supply itself, a bag of cables and an adapter plate. The latter allows for the PSU to be installed in a regular ATX Case, although why you would do this is a mystery to me…

At the time of review the Lian Li PE-550 550W SFX Power Supply is available from Overclockers UK for approximately £120 and comes with a 3 year warranty.



courtesy of Lian Li


Model PE-550
Type SFX-L
Dimensions (D)130mm
Input Voltage 100-240Vac
Input Current 115V /10A – 230V/5A
Input Frequency Range 115V/50Hz – 230V/60Hz
PFC (Power Factor Correction) ACTIVE PFC (>.95)
Power Good Signal 100~500 ms
Efficiency >86.5% (89.5% max)
Max Output Capacity 600W (10s)
Operation Temperature 0-40℃
MTBF >100,000 hours
Protection OVP / UVP/ OTP / OCP/ OLP/ OPP/ SCP
Safety UL / CB / FCC / Bauart gepruft
Fan 120mm Fan voltage varies with the ambient temperature and/or output power.
Cable 24/20-Pin motherboard connector(400mm)x1

8/4-Pin EPS / ATX 12V connector(400mm)x1

8/6-Pin PCIE connector(150mm/400mm)x1

* SATA connector(100mm/100mm/200mm/300mm)x3

4-Pin Floppy / 4-Pin Peripheral connector (100mm/200mm/200mm/300mm)x1

Warranty 3-year
Semi-fanless 0 DB at low temperature/power load

* NOTE: The PE-550 PSU only comes with x2 SATA connectors and not x3 as suggested by the Lian Li Specifications above


* Additional details available here


First Impressions



NOTE: There may be some debate as to what is the top of a PSU as the physical top often features a fan, but when installed the fan normally faces down, now suggesting that this is in fact the bottom! So, from now on I’m calling the side with the fan the top! 😉

Obviously the first thing that strikes you about the Lian Li PE-550 is its diminutive size. When you first see a SFX sized Power Supply you wonder (wish) that all Power Supplies were this size, especially when you can get up to 750W. As you can see the top of the PSU is not much bigger than the 120mm fan within.


Looking around the sides of of the PE-550 we find a specification sticker on the left detailing model, power output, volts and amps etc. Looking at the back of the PSU we see a standard layout with a grilled section on the left and power socket and switch on the right. Looking at the front of the PSU we see all of the main sockets that support the six supplied cables (see below). Note the two blue sockets designed to support PCIE power for up to two Graphics Cards. So it’s a little strange and disappointing that Lian Li only provide one PCIE 8/6 power cable!?



As you can see from the image above left the cables for the Lian Li PE-550 are supplied in a soft cloth bag, it does the job but it’s poor compared to other cable bags that we’ve seen from the likes of Corsair and Silverstone. In that bag (and despite what Lian Li suggests) there is x1 24-pin, x1 8-pin, x1 8/6-pin, x2 SATA and x1 Molex/floppy power cables. All of which are flat. The one with the blue connector is the PCIE power connector that supports up to x2 8-pin connections. There are also some screws (x3) for the PSU itself and x4 screws for the SFX to ATX adapter plate. NOTE: This Power supply was supplied with an EU power cable and not a UK power cable.


Cable Details



Hardware Installation


  • Test Rig Setup

  • Case SilverStone Primera PM01 Power Supply Lian Li PE-550B
    Motherboard ASRock Fatal1ty Z170 GAMING K6 CPU Intel Core i5-6600K
    CPU Cooler ID-Cooling FrostFlow 120 RAM G Skill Ripjaws 4 16GB
    Graphics Card Asus GTX 1080Ti “Founders Edition” SSD (M.2) Samsung SM951 512GB
    SSD Kingston SSDNow 200 v+ 60GB HDD Seagate 2TB SSHD


    Now while the performance of the Lian Li PE-550 was tested with our standard Test Rig (see above) it was also used as part of a full PC build. For this build we decided to use a BitFenix Portal ITX Case as the Lian Li is (after all) an SFX Power Supply, this size PSU is required for the Portal. Therefore we did not need to use the supplied SFX to ATX adapter plate. Just three screws are required to hold this little PSU in place. But wait there’s a problem…



    This was due to the fact that the PSU mounting holes didn’t line up. This was due to the position of the Case lug and the power socket as they were fouling one another (see above right). Now whether the lug is too big or whether the PSU’s socket is misaligned I don’t know but the answer was a bit of filing.


    Testing Methodology/Setup


    When it comes to testing Power Supplies there’s very little else you can do other than put the PSU under load and measure the voltages. As this is not a very real world test (as it only takes seconds to setup and record), we have employed a more real world test. For more details on our thoughts regarding Power supply testing check out this article.

    The Power Supply is put under a real world load for 1 hour, while running both Unigine Superposition and Prime 95 (Blend) simultaneously. Power Supplies under 750W are tested with a single Nvidia GeForce GTX 1080Ti Graphics Card while Power Supplies of 750W and above are tested using two 1080Ti Graphics Card to ensure the PSU gets a real workout. 😉


    Hardware Performance



    As you can see from the above image, the Lian Li PE-550 550W Power Supply completed and passed our burn-in tests. In our single GPU test the voltages were stable at (3.184v, 4.944v & 11.808v), but all were below optimum levels. All voltages are within the Intel minimum limits of (3.14v, 4.75v & 11.40v) but as you can see the 3.3v rail is getting a little close for comfort. 😮 Having said that throughout testing and during burn-in no instability was encountered.


  • x1 Nvidia GeForce GTX 1080Ti

  • The maximum power draw (at the wall) during testing was recorded at 419.4 watts, suggesting that this Gold rated Power Supply was delivering approximately 370 watts to the system due to its 88% efficiency at an approximate 77% load.


    For more information regarding Power supply testing and the 80 Plus Efficiency rating check out this article.


    Final Thoughts


    If you’re looking for a small SFX PSU then the Lian Li PE-550 550W Power Supply is a good option. It offers up a decent feature set for the asking price, delivers good performance and the PSU remained quiet at all times. Only the slightly below voltages during our torture test let it down, although they were all still within Intel’s guidelines.

    The Lian Li PE-550 550W Power Supply arrived at pcG in a simple small (obviously!) black box, the contents were found to be both well packaged and presented. Although the cloth cable bag seems, well, a little cheap. There’s also not many cables but there’s enough for a decent Gaming PC as long as you’re not planning on SLI or Crossfire as there’s only one PCIE power cable.

    From a pure asethetics point of view the Lian Li PE-550 is a good looking PSU, with nothing to make it stand out for the better or the worse. It is equipped with a single 120mm fan that will not spin unless load is greater that 30%. The PSU is supplied with x1 24-pin, x1 8-pin, x1 8/6-pin PCIE, x2 SATA and x1 Molex/floppy power cables. This is despite the fact that the Lian Li specifications show x3 SATA cables. Also worth noting is the fact that all cables are flat, now I’m still on the fence as to whether this is good or bad…

    Of course the most important aspect of a PSU such as this is not just the power/performance but the fact that this is a SFX Power Supply. That means that all of its 550W (750W also available) is wrapped up in a PSU measuring just (D)130mm x (W)125mm x (H)63.8mm. In fact once you’ve seen a SFX Power Supply you’ll likely wonder why all PSUs aren’t this size.

    During our combined CPU/GPU torture test the Lian Li PE-550 held up well pulling 419W at the wall. It managed to keep all voltages within Intel guidelines with the following (3.184v, 4.944v & 11.808v) . But note that all are south of where they should be and the 3.3v rail is getting close to Intel minimum limit of 3.14v. That said I had no stability issues while using this PSU and no crashes during the test.

    If you are looking for a SFX Power Supply then this Lian Li offering pretty much ticks all of the boxes, as it does everything it says on the tin. But if you’re thinking of pushing it hard the 750W version may be a better bet…



    Please Share, Like & Comment below, we really value your thoughts and opinions…

    Overclockers UK

    Lian Li PE-550B


    Design/Quality pcGameware awards the Lian Li PE-550 a Silver

    Many thanks to Lian Li for providing this sample for review


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