Seasonic X-Series: X-850 Power Supply Review

Seasonic is a long time favorite of HardOCP editors as you will find a Seasonic PSU in many builds we have done over the years. Today Seasonic pushes its X-Series forward just a bit more building its first gold efficiency rated fully modular enthusiast power supply. But will it blend?


In the power supply realm, when consumers think of quiet and efficient power supplies one of the first company that comes to mind is Seasonic. Today, we have our 13th (lucky number 13!) look at a Seasonic branded unit. This review covers another entry in Seasonic’s excellent X-Series line of power supplies the X-850 (SS-850KM3 Active PFC F3). This is NOT the original X-850 which carries a model number of SS-850KM Active PFC F3. Be careful!

Seasonic is one of the older companies producing consumer power supplies having been founded in 1975 and entering the PC power supply production market in 1980. During that more than 30 years as a company Seasonic has cultivated lines of power supplies that are today some of the standard bearers for efficiency and quiet computing. This focus, and its reputation for quality, has lead to a real explosion in production as Seasonic can be found providing OEM services on various model lines for Antec, Corsair, XFX, PC Power and Cooling, and of course under its own Seasonic brand.

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Lucky 13!

The Seasonic X-850 is the 6th power supply we have seen from Seasonic’s X-Series of units. To date, all of those members of the X-Series have been winners and the line has been around long enough that Seasonic is starting to roll out revisions to some of the earlier models. Today’s X-850 (SS-850KM3 Active PFC F3) is a revision of the original X-850 (SS-850KM Active PFC F3). However, among the original X-Series units we reviewed the X-850 was not one of those units so, while a revision, today’s X-850 is a "new" unit to us. Given the results from the other X-Series units we have reviewed though, we certainly have high expectations for this unit today. Indeed, among Seasonic’s offerings the X-Series slots in right under its Platinum series as one of its higher end offerings. With that position in the pecking order we have to see what Seasonic has to say about this unit:

Seasonic Patented DC Connector Panel with Integrated Voltage Regulation Module

Seasonic’s Patented Fully Modular Design while minimizing voltage drops and impedance, it greatly maximizes efficiency and cooling to enhance overall performance and reliability.

* Patent #: US8.040.686, TW381825, CN1552150, JP3171420.

Patent Pending: US, DE

Seasonic Hybrid Silent Fan Control آ– S2FC and S3FC

The industry first, advanced three-phased thermal control balances between silence and cooling.

The Hybrid Silent Fan Control provides three operational stages: Fanless, Silent, and Cooling Mode. In addition, there is a switch provided to allow for manual selection between the Seasonic S2FC (fan control without Fanless Mode) and the S3FC (fan control including Fanless Mode).*Patent #: TW410250, CN808637, CN1980304. Patent Pending: US, JP

Sanyo-Denki San Ace Silent Fan

The world-renowned Sanyo Denki Ball bearing fans are made of the highest quality components to ensure maximum quality and performance. The use of spoon shaped high-density plastic fan blades with smoothed leading edges, strict tolerance ball bearings and precision copper axel are just some features to ensure ultra-low noise performance and quality. In addition, the fan uses 3 balancing points, instead of the industry standard of 2 points, to ensure perfect balance and rotation. The Sanyo Denki fan is a perfect match to the class leading Sea Sonic Hybrid Silent Fan control for the absolute top performance of the industry.

With little of substance there other than some advertising points about specific features (that we have seen before), let’s move on and see what we have to look forward to when we purchase the Seasonic X-850 power supply in terms of documentation, accessories, cable count, rail layout, output characteristics, and general build quality.