Seasonic X-1250 1250W Power Supply Review

Seasonic makes some of the best enthusiast computer power supplies in the world. It has long produced some of the cleanest power producing PSUs along with being some of the quietest on the market. The new fully modular X-1250 sports many enthusiast features and touts gold level efficiency. Is this new X-1250 worthy?


In the power supply realm, when consumers think of quiet and efficient power supplies one of the first companies that comes to mind is Seasonic and today we have our tenth look at a Seasonic branded unit. This review covers another entry in Seasonic’s X-Series line of power supplies the X-1250 (SS-1250XM).

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, PC Power and Cooling, and of course under its own Seasonic brand.

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Is it as Good as Gold?

The Seasonic X-1250 is the 10th power supply we have seen from Seasonic and to date it is easily the largest capacity unit we have seen from the company. However, we have seen a version of this particular unit before when we reviewed the XFX ProSeries 1250W and this basic design has been used in a number of units since the introduction of the Platinum-1000. In that time, this design has performed extremely well and has represented a great product as well as a great value to users. Given that there so much history with this vendor, and this particular design, we really aren’t expecting a lot of surprises today; just a more of the same extremely solid performance we have seen before. Before moving on though, let’s see what Seasonic has to say about this unit:

Full Modular Design (DC to DC)

Common to all X-Series power supplies, the new X-1050 and X-1250 feature the unique integrated DC connector panel with onboard VRM (Voltage Regulator Module) that enables not only near perfect D-to-D conversion with reduction of current loss / impedance and increase of efficiency but also a fully modular DC cabling that enables maximum flexibility of integration and forward compatibility.

Seasonic Patented Hybrid Silent Fan Control-S2FC & S3FC

An industry first, advanced 3 phased (Fanless, Silent and Cooling Mode) thermal control balances between silence and cooling. In addition, for X-1050 & 1250 a selector switch is provided to allow you to select between the Seasonic S2FC control, without fanless mode or the S3FC fan control, with fanless mode.

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, let’s move on and see what we have to look forward to when we purchase the Seasonic X-1250 power supply in terms of documentation, accessories, cable count, rail layout, output characteristics, and general build quality.