Seasonic X-850KM3 850W Power Supply

Power Supply

Seasonic X-850KM3 850W Power Supply Main Picture

Seasonic X-850KM3 850W Power Supply Picture 22645Seasonic X-850KM3 850W Power Supply Picture 22642
The X-Series 850W power supply from Seasonic is a very capable unit, offering enough wattage for most configurations we build - while also remaining highly efficient and quiet. Like all members of the X-Series line, the 120mm fan turns off at low power draw levels - and thanks to its 80PLUS Gold 90% efficient rating the fan is almost always going to be off when the computer idles or is just under basic usage. When more is required of it, though, the fan will kick on and keep the unit running cool.
Ruben Romero (Tier 3 Integration Lead)
Ruben Romero (Tier 3 Integration Lead) Says:
Seasonics new revision to the KM3 model of the X-850 added a Hybrid/Normal switch like the X-1050 has to either have the fan run constantly when in use or to turn off the fan when operating temperatures are low enough to not need additional airflow. One other change to the power supply was adding a dedicated CPU2 modular plug instead of having to use one of the PCI-E plugs like the previous revision had.
John Dinning (Research and Development Engineer)
John Dinning (Research and Development Engineer) Says:
This 850-watt entry in SeaSonic's X-series line of power supplies is a great option for configurations that need to draw a little extra power. It offers most of the same features we like in the lower-powered 650 model, including a temperature-controlled fan for quiet operation and fully modular design. Being a higher-wattage supply, however, it has a little extra headroom for power-hungry CPUs or video cards. This is a great step up if you need more power than the 650W offers, but don't need to go all the way up to the 1000W range.
Josh Raye (Research and Development SME)
Josh Raye (Research and Development SME) Says:
The Seasonic X-850 has everything a high-end power supply should offer. It has modular design, high efficiency, consistent voltages, and very quiet operation. In fact, this unit is completely silent in most idle situations, because the 120mm fan only cuts on when the system has reached a certain load/temperature threshold. Even then, I would say it's far from loud. In regards to it's wattage, 850W is more than adequate for the majority of configurations.

Model: SeaSonic SS-850KM3 Active PFC F3


Maximum Power 850 W
Standard Compliance CB, cTUVus, CCC, TUV, GOST-R, BSMI, CE, UKR, FCC, C-tick
Peak Efficiency 90 %
Efficiency Certification 80 PLUS Gold
Cooling System Quiet 120mm Fan
Safety Compliance OPP, OVP, UVP, SCP, OCP, OTP
Materials Compliance WEEE, RoHS
Power Distribution
+3.3V rail 25 amps
+5V rail 25 amps
+12V1 rail 70 amps
Combined +12V Maximum 70 amps
Molex 5
Floppy 1
PCIe 8-Pin 6
CPU Power 8 pin 1
CPU Power 8/4 pin 1
External Connector Type C13
Height 86 mm (3.4 in)
Width 150 mm (5.9 in)
Depth 160 mm (6.3 in)
Voltage 100-240 Vac
Frequency 50/60 Hz


  • 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.

Special Features:
1. 80PLUS Gold Certified Super High Efficiency
2. Full Modular Cabling Design
3. Patented DC Connector Module with Integrated VRM [Voltage Regulator Module]
4. DC to DC Converter Design
5. Seasonic Hybrid Silent Fan Control
6. Sanyo Denki San Ace Silent Fan
7. Conductive Polymer Aluminum Solid Capacitors
8. Highly Reliable 105℃ Japanese Brand Capacitors
9. Tight Voltage Regulation [+/-3%]
10. Active Power Factor Correction [99% PF Typical]
11. High +12V Output
12. High Current Gold Plated Terminals
13. Dual Sided PCB Layout
14. Ultra Ventilation [Honeycomb Structure]
15. Multi-GPU Technologies Supported
16. All-in-One DC Cabling Design
17. Easy Swap Connector
18. Universal AC Input [Full Range]
19. 7 Years Warranty