Seasonic Focus Plus Gold 850 Modular Power Supply, 80+ Gold, 850W

MX71371 Focus Plus Gold 850 Modular Power Supply, 80+ Gold, 850W
MX71371 Focus Plus Gold 850 Modular Power Supply, 80+ Gold, 850W

Product Info


The Center of Attention

Seasonic engineers have created a brand new product line based on advanced technology emanating from many years of intensive active research. The result of this development is the solid FOCUS+ Series, which implements modern design and shows outstanding electrical performance. This power supply is small and entirely modular, which will be hard to resist.

80 PLUS® Gold Design
Seasonic was the forerunner of creating the very first 80 PLUS® Gold certified power supply on the market and since that time it has built a very popular Gold series lineup that covers a full power range of power supplies with impeccable performance and efficiency. The FOCUS PLUS Gold Series achieves 80 PLUS® Gold certification with its 90% efficiency at 50% system load.

Cable-free Connection Design
Seasonic’s engineers have implemented a new design feature, where instead of cables; the back panel and the PCB (Printed Circuit Board) are connected by a copper plate. This breakthrough solution not only lowers the chance of production errors during manual insertion but it also improves output power quality.



  • High Efficiency, 80 PLUS® Gold Certified
  • Single 70A Rail powers multiple Video Cards
  • Fully Modular Cabling Design
  • Compact Size: 140 mm long
  • 120mm Fluid Dynamic Bearing (FDB) Fan w/ Seasonic Hybrid Silent Fan Control
  • S3FC: Fanless until 30% load
  • Gold Plated Connectors
  • Highly Reliable Japanese 105° C Aluminum Electrolytic Capacitors
  • Tight Voltage Regulation: 12Vdc, 5Vdc & 3.3Vdc ±3%
  • Internal Cable Free Connection Design
  • Seasonic 10 Year Manufacturer Limited Warranty

Hybrid Silent Fan Control


The industry’s first, Seasonic patented, advanced three-phased thermal control achieves optimal between silence and cooling. This Hybrid Silent Fan Control functions in three operational stages: Fanless Mode, Silent Mode, and Cooling Mode. There is a switch at the back of the power supply which allows users to customize their cooling needs by selecting between the Seasonic S2FC (fan control without Fanless Mode) and the S3FC (fan control including Fanless Mode).

  • Reduced noise without increase in temperature
  • Extended fan life due to the reduced number of fan rotations
  • Optimized heat dissipation at all times
  • Unsurpassed silent performance in Fanless Mode

The Fan Control Button


The fan control button can be found on the back of the back of the FOCUS PLUS power supply, next to the power switch.

The image here illustrates how to select different fan control modes to suit your need. Do not press the button if you wish to include the Fanless Mode, which means the fan in the power supply will not spin when the power supply is under light loads.

Press the button if you wish to have the fan spin at all times, even at lower loads.

Fluid Dynamic Fan Bearing

High performance Fluid Dynamic Bearing (FDB) fans are designed to take advantage of the impact absorbance effects of oil. They are extremely reliable and generate considerably less operating noise and heat than ball bearing fans. The lubrication of the bearing surface reduces friction and vibration and therefore lowers overall power consumption. Due to the effortless, quieter rotations and its robust construction, this reliable fan technology also greatly increases the lifespan of the fan.


How FDBs Work
When the fan shaft rotates, high pressure oil drifts along the grooves of the bearing sleeve to generate a thin layer of lubrication between the bearing faces. As the speed increases, so does dynamic oil pressure and the shaft is lifted from the bearing to create smooth, effortless rotations. The herringbone shape of the groves helps to efficiently channel the lubricant and avert leakage.

Additional Information:

Visit the Manufacturer Product Web Page for Full Details

Download the Manufacturer Product Manual

Download the Manufacturer Specification Sheet


Make and Model Seasonic FOCUS PLUS 850 GOLD 850W Power Supply
Part Number SSR-850FX
Input Voltage 100 ~ 240Vac, 50/60Hz
Efficiency 80+ Gold Certified
Maximum Load
Voltage +3.3V +5V +12V -12V +5Vsb
Current 20A 20A 70A 0.3A 3A
Wattage 100W 840W 3.6W 15W
Combined Wattage 850W
Cooling 1x 140mm FDB (Fluid Dynamic Bearing) Cooling Fan
MTBF 100,000 Hours @ 25° C, 15 ~ 65% RH (non-condensing)
Protection Over Current protection (OCP)
Over Voltage protection (OVP)
Over Power protection (OPP)
Over Thermal protection (OTP)
Short Circuit protection (SCP)
Under Voltage protection (UVP)
Connectors 1x Motherboard 20+4 pin Connector (610mm)
2x CPU 4+4 pin Connector (650mm)
6x PCI-e 6+2 pin Connectors
10x SATA Connectors
5x 4-pin Molex™ Peripheral Connectors
1x 4-pin Floppy Connector
Form Factor ATX 12V
Temperature Operating: 0 ~ 50° C
Compliance BSMI, CB, CCC, CE, cTUVus, EAC, FCC, TUV
Dimensions / Weight  
Dimensions 140 x 150 x 86mm
Net Weight N/A