Seasonic FOCUS Plus 850 Platinum


Sea Sonic Electronics Co., Ltd was founded in 1975 with its headquarters in Taipei, Taiwan, it is a company specialized in the manufacturing of power supplies for the consumer & industrial markets. In 1981 the company starts the production of power supplies for PC type of systems, being one of the first manufacturers to do so.
SeaSonic manufactures and sells power supplies under its own brand and is also the OEM manufacturer for many other power supplies companies. This makes Seasonic one of the well-known and respected brands in the industry.


Official product link:


Packaging and accessories

The power supply comes packaged in a cardboard box with a glossy surface that features a silver and black sunburst effect. On the front side, the name of the power supply and the Focus series logo are encased in a black triangle alongside the 80Plus Platinum rating.


The sides of the box present the general specifications of the power supply starting with the dimensions and the protections offered. At the top side there is the manufacturer’s logo alongside the Focus Plus Platinum series emblem.


The back side of the box presents the features of the product; on the upper part we find the Seasonic logo while on the right side there is the power supply model. On the lower corner, the Focus Plus Platinum series emblem is placed.



The product comes with the following accessories:
– 1x Manual
– Quick installation guide
– Velour bag
– 3x Velcro cable straps
– 1x Focus Plus Badge
– 4x Metallic screws
– 12x Zip ties



Model: SSR-850PX
Max. DC Output: 850W
Efficiency: 80PLUS® Platinum
Modular: Full Modular
Form Factor: Intel ATX 12 V
Operating temperature: 0°C – 50°C
Fan Size: 120 mm
Fan bearing: Fluid Dynamic Bearing
Fan Control: Hybrid Silent fan Control
– Over Power Protection
– Over Voltage Protection
– Under Voltage Protection
– Over Current Protection
– Over Temperature Protection
– Short Circuit Protection
Connectors and cables:
– 1x 24 pin ATX connector (610mm)
– 2x CPU (8/4 pins) (650mm)
– 3x PCIe (8/6 pins) (675mm)
– 1x SATA (450mm)
– 1x SATA (350mm)
– 5x 4 pin Molex (450mm)
– 1x FDD (+101mm)
Dimensions: 150 mm (W) x 140 mm (L) x 86 mm (H)
Weight: 1.9 kg
MTBF @ 25 °C, excl. fan: 150,000 hours
Life Expectancy: 50,000 hours at 40 °C, 15 % – 65 % RH
Compliance: Energy Star, RoHS, WEEE, ErP Lot 6, REACH\
Warranty: 10 years


– 80 PLUS®Platinum: The 80 PLUS® Platinum certification guarantees greater than 90 %, 92 % and 89 % efficiency at 20 %, 50 % and 100 % operating loads, respectively. The Seasonic Platinum Series represents the highest level of technology and efficiency achievement of Sea Sonic during its 40 years of commitment to engineering excellence.
– 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.
– Fluid Dyanamic 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.
– Ultra-Stable Voltage Regulation: Seasonic has implemented and even stricter voltage regulation which entirely eliminates negative deviations and keeps voltage 80% tighter than Intel specifications and 66 % tighter than top reviewers recommend. The result of clean output power is quicker CPU response and a better overclocking performance.
– 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.


Visual inspection

The FOCUS Plus 850 Platinum model uses a single 120mm fan for the active cooling of the internal components, this fan features Seasonic’s Hybrid Silent fan control system in three-phases, the fan can turn off in the case of low load. Like all units that are part of the Focus Plus series, the 850 Platinum uses a case that is reduced in size, the dimensions for it are: 150 mm (W) x 140 mm (L) x 86 mm (H).


The sides of the power supply are decorated with symmetrical indents that complete the overall look of the power supply, the lower side is covered by a two-tone Focus Plus Platinum emblem while the Seasonic logo is placed on the upper left corner.


The back side is simple; the metallic panel of the case is perforated to facilitate the exhausted air pushed by the 120mm fan installed at the front of the unit. The left side features the AC power connector alongside the Hybrid Silent fan control switch.


On the front side of the power supply there are the 12 modular connectors the manufacturer’s and Focus Plus emblems. Each connector features one plastic clip to hold the cables once connected and in addition, each one is labeled in white to ease the installation process of the power supply.


On the top of the Power Supply we have the label with the specifications and certification of the PSU.


The cables of the Power Supply are completely black and flat to ensure an easier installation and wire management.


The fan used is provided by Hong Hua, model HA1225M12F-Z specifications: 12 V, 0.45 A, 2050 RPM, 120 mm. This model uses a rotor that features the Fluid Dynamic Bearing mechanism, offering a better lubrication system and lower noise operation while lasting longer. The fans using this system are known to work for more than 50,000 hours. In addition, the fan is connected to the PCB using a 2-pin Molex connector.


The Focus series uses a new platform developed for the budget series of power supplies, however not cutting down the quality, especially in terms of internal components. The passive cooling is done by four metallic heatsinks while the active cooling is achieved by the 120mm Hong Hua fan.


Behind the AC slot there are two Y capacitors and one X capacitor starting the filtering path. A small PCB is also fitted to the whole assembly.


In the APFC section there is installed a single capacitor manufactured by Nippon Chemi-Con with the following spec: 6500μF/400V with a maximum operating temperature of 105°C. Next to it we find the main coil alongside a pair of transformers.


On the secondary PCB of the Modular system there are two main coils alongside seven capacitors. Between the main and secondary PCBs the VRM for the minor rail are mounted.


On the PFC side we have a single Hongfa HF46F-G relay alongside two Infineon 5R190CE voltage regulators.


The capacitors used in the 850 Plus Platinum are manufactured by Nippon Chemi-Con.



The following system was used to test the Power Supply:
– Processor: Intel i5 4690K @ 4.5 GHz
– Motherboard: MSI Z97 Gaming 9 ACK
– RAM: 16GB Crucial Ballistix Tactical
– GPU: NVIDIA GeForce GTX 1070 Founder’s Edition
– SSD: Samsung 840 EVO 120GB
– HDD: WD 1TB Blue
– CPU Cooler: SilverStone Tundra TD02(Custom) with NoiseBlocker eLoop B12-PS
– Display: AOC i2769VM
– Case: Phanteks Enthoo Luxe White

The above system has a power consumption of approximately 495W when in full load and 67W when idle, in order to test the efficiency of the Power Supply, the power draw of the system was measured at the wall socket. Also, the voltages were measured on the +12v +5v and +3.3v using a multi-meter.
To load the system to its maximum the stability test of the AIDA64 Extreme (5.97.4600) was used with Intel Burn Test V2.
The Power Supply was tested with the system both idle and at maximum load.


Power Supply efficiency


For rail voltage tolerance levels, ATX (Power Supply Design Guide) specify that a 5% variable fluctuation is acceptable.

Voltage oscillation idle


Voltage oscillation load


The noise level was measured at three different distances from the fans (10cm, 20cm, 30cm.) the noise was measured with a margin of error of ± 5 db.


Final thoughts

The Seasonic FOCUS Plus 850W Platinum features a brand new platform that is shared across the whole Focus range, the 850PX model having an efficiency of 92% and up. The build quality on both the outside and inside is very good, the soldering is immaculate and the internal layout is designed to aid with the passive and active cooling of the unit. The Hybrid Silent mode allows for this power supply to be completely silent when it is not being heavily used, but when the fan does start it reaches a maximum sound value of 31db.
The cables are flat and completely black; the only cable being covered in sleeving is the 24Pin ATX cable for powering the motherboard.
The performance of the power supply is excellent thanks to the internal components of this new platform, the efficiency of this unit when in load, reaches a value of 92% while the voltage oscillation is minimal.

In conclusion, the FOCUS Plus 850 Platinum model is one of the high end models of the Focus budget range offered by Seasonic, being the proof that budget oriented power supplies do not have to make compromises in either performance or overall quality.
The internal build quality is great, all the capacitors inside are manufactured by Nippon Chemi-Con while the coils are covered at the base with silicone to prevent vibrations and unwanted noises caused by the current.
With these units just like with the high end power supplies, Seasonic offers a warranty of up to 10 years, showcasing the performance and more important, the reliability of these units.

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