Seasonic Platinum Series Fanless 520 W Review 19

Seasonic Platinum Series Fanless 520 W Review



We would like to thank Seasonic for supplying the review sample.

Seasonic is one of the most experienced PSU OEMs, which makes every new product they release pretty interesting to a major portion of users and most PSU reviewers. Until recently, their portfolio only included two Platinum efficiency units, the SS-1000XP, which we have reviewed in the past, and the SS-860XP. Their other high-end models only feature Gold efficiency, but that situation is about to change significantly with the introduction of three new Platinum models with 760 W, 660 W, and 520 W capacity, the latter of which is a fanless unit.

Today, we will rigorously evaluate the Seasonic Platinum Series Fanless 520 W PSU. Its model number is SS-520FL, and it packs several improvements over the X-460FL: Seasonic's previous fanless PSU flagship. Capacity has, for starters, increased by 60 W and efficiency has been upgraded to Platinum. The SS-520FL's new platform is significantly different to the one its predecessor used. It allows for better performance and improved efficiency at low loads, which is an area the X-460FL didn't do so well in. The SS-520FL also comes with a fully modular cabling design, which will thrill most users, a well-ventilated enclosure that allows for optimal heat dissipation, a single +12V rail, and a seven-year warranty. The number of PCIe connectors has not changed. The unit only comes with two PCIe connectors. We were really expecting Seasonic to equip this unit with an additional two connectors since the capacity has increased, which would have made the SS-520FL an option with SLI or Crossfire configurations. We are pretty sure that many users out there will be let down by the lack of four PCIe connectors, and Seasonic should look into this issue as soon as possible.


Seasonic SS-520FL Features & Specs
Max. DC Output520W
Efficiency80 PLUS Platinum
Operating temperature0°C - 50°C
ProtectionsOver Voltage Protection
Under Voltage Protection
Over Current Protection
Over Power Protection
Over Temperature Protection
Short Circuit Protection
Dimensions150 mm (W) x 86 mm (H) x 160 mm (D)
Weight2.0 kg
ComplianceATX12V v2.31, EPS 2.92
Warranty7 years
Price at time of review (exc. VAT)$149.90 (MSRP)

Efficiency is Platinum and the maximum operation temperature is 50°C, which is pretty special given that the unit doesn't have a fan to cool it down. It has all available protection features, and that includes OTP (Over Temperature Protection), something that is pretty crucial to a fanless unit. The unit's footprint is pretty compact with a width of 160 mm, and its warranty is really long at seven years. Seasonic seems to be pretty confident about this model's longevity even though the lack of a cooling fan means higher internal temperatures than those found inside a normal PSU. The price looks pretty stiff, but is, actually, fine for a fanless PSU, especially if we consider that other fanless units with less features and a lower performance are much more expensive.

Seasonic SS-520FL Power Specs
Max. Power20A20A43A2.5A0.5A
Total Max. Power520W

The single +12V rail can deliver the unit's full power, which makes it quite strong and easily capable of supporting two mid-level VGAs. Seasonic will hopefully consider equipping each cable with two PCIe connectors instead of one.

The minor rails have enough power to meet the requirements of a modern system and the PSU's overall capacity. The 5VSB rail does feature the minimum power that a modern PSU should deliver on this rail.

Cables & Connectors, Power Distribution

Modular Cables
ATX connector (600mm)20+4 pin
4+4 pin EPS12V (650mm)1
6+2 pin PCIe (600mm)2
4 pin Molex (410mm+125mm+125mm)3
4 pin Molex (305mm+125mm)2
SATA (390mm+115mm+115mm)3
SATA (300mm+115mm)2
FDD (+150mm)1

All cables are pretty long, and the distance amongst all connectors will suffice in most cases. The number of SATA and peripheral connectors is adequate for the capacity of the PSU, but the number of PCIe connectors is pretty small, and two additional PCIe connectors would be ideal.

The EPS and PCIe cables are fully sleeved, but the SATA and peripheral connectors use ribbon cables. All gauges are black, which will help modders hide them well. All connectors use 18AWG wires as recommended by the ATX spec.

We do not have anything to comment on about this PSU's power distribution since it features a single +12V rail.


The box is of medium size and features a nice platinum color that probably refers to the efficiency rating of the PSU. A significant portion of the front's real-estate is covered by a photo showcasing the PSU's well-ventilated enclosure. The face of the box also contains the Platinum efficiency badge, Seasonic's logo, the series name, and the capacity description on a black background.

One of the two sides has the unit's specification table and the output ratings of all rails.

Seasonic was kind enough to provide a photo of the unit's internal on the rear side of the box; for interested users. A paragraph explaining the differences between 80 Plus certifications, and the advantages of its higher 80 Plus Platinum certification, adorns a corresponding table. We also found references to Seasonic's patented modular panel that integrates the DC-DC converters of the minor rails, the tight voltage regulation, the unit's fanless operation, the use of Japanese polymer caps, the seven-year warranty, and the gold terminals of the modular connectors.

On top of the box are a multilingual features description, the platinum badge, and the SS-520FL's series name.

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