Seasonic PRIME 850W Gold



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 multicolored cardboard box with a black background and gold accents.
The front side of the packaging is simple, the background is formed from geometric shapes. On the right side there are placed the name & capacity of the power supply, while on the left side there are the Seasonic emblem, PSU certification and the warranty offered by the manufacturer.

The sides of the box present a few features of the power supply in eight different languages and the specifications of the product.

The back side of the box presents the features of the product, on the upper part we find printed the Seasonic logo while on the right side there is a general image of the power supply. On the lower left corner, there is a QR code and the “Made in Taiwan” certification.

The power supply is packaged in a textile bag while the cables are packaged in sealed plastic bags, these are inside a separate cardboard box.


The product comes with the following accessories:
–    1x Manual
–    Quick installation guide
–    Velour bag
–    5x Velcro cable straps
–    1x Seasonic Prime Sticker
–    1x Seasonic Badge
–    4x Metallic screws
–    8x Zip ties



Model: PRIME 850W Gold
Max. DC Output: 850W
Efficiency: 80PLUS® Gold
Modular: Full Modular
Form Factor: Intel ATX 12 V
Operating temperature: 0°C – 50°C
Fan Size: 135 mm
Fan bearing: Fluid Dynamic Bearing
Fan Control: Premium Hybrid 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 8 pin EPS12V (650mm)
–    3x 6+2 pin PCIe (675 + 75 mm)
–    10x SATA (450 + 120 + 120 + 120 mm) / 1x 450 + 120 + 120 + 120 mm
–    5x 4 pin Molex (400 + 120 + 120 mm) / 1x 350 + 120 mm
–    1x FDD (+101mm)

Dimensions: 150 mm (W) x 170 mm (L) x 86 mm (H)
MTBF @ 25 °C, excl. fan: 150,000 hours
Life Expectancy: 50,000 hours at 40 °C, 15 % – 65 % RH
Weight: 2.2 kg
Compliance: Energy Star, RoHS, WEEE, ErP Lot 6, REACH
Warranty: 12 years


80 PLUS®Gold: 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 highly efficient 80 PLUS® Gold certification guarantees greater than 87 %, 90 % and 87 % efficiency at 20 %, 50 % and 100 % operating loads, respectively.
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.
Premium Hybrid Fan Control: Seasonic’s vast experience in designing the most silent and efficient power supplies on the market was translated into the development of Hybrid Mode; a state-of-the-art fan control that enables users to keep the overall fan noise at the lowest possible level.
Micro Tolerance Load Regulation: Seasonic’s latest design keeps the output voltage within a very tight range, achieving under 0.5 % (1 % for 1000 W and above) load regulation. This impressive electrical performance and stability makes this power supply an ideal choice for high-performance systems.
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.
Gold Plated Connectors: Gold plating critical connector pins (motherboard, CPU and PCIe cables) extends the lifetime of the connectors and greatly increases the efficiency of current transmission.


Visual inspection

The Prime line distinguishes itself from other power supplies through its mainly honeycomb design on the front side, it is composed out of two metallic segments. In the case of the 80PLUS Titanium certified models, the top plate is chromed in order to offer a better representation of the certification.
The power supply has the following dimensions: 150 mm (W) x 170 mm (L) x 86 mm (H), and thus being larger than the normal ATX power supply.

The front grill which covers the 135mm fan is made out of two metallic plates that overlay each other, in the middle there is the Prime line name. In addition, the front side is perforated with a honeycomb pattern.


On the back side the PSU is perforated for a better airflow. On the right side, there are placed both the on-off switch, AC slot and the Hybrid mode switch.


On the sides there are perforated slots which maintain the overall look of the power supply and thus, offers a different deign from the previous models. On the upper part, there is the manufacturer’s logo while on the right there are the Prime series name and the power supply certification.


The front side is occupied by the 12 connectors for the modular cables, these are individually labeled and each cable is not compatible with a different connector.


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 covered in sleeving almost to the end of the connector.  The secondary cables are flat to ensure an easier installation and wire management.


The fan used is provided by Hong Hua, model HA13525H12F-Z specifications: 12 V, 0.5 A, 2000 RPM max, 135 mm. In addition, the fan is connected to the PCB using a 2-pin Molex connector.
This model is Fluid Dynamic Bearing type, a system that is ideal for low noise operations and endurance.


The Prime line uses a new platform, proprietary of Seasonic. The Hybrid mode allows the power supply to function with the fan switched off until a temperature stage is reached.
The active cooling is done by the Hong Hua 135mm fan while the passive cooling of the components is ensured by 4 metallic heatsinks.

Behind the AC receptacle there are two Y capacitors and one X capacitor. Also, the AC slot is protected by a metal case.
On the main PCB, the filtering is continued by four Y capacitors, one X capacitor and two filtering chokes.

The power slot is connected to the main PCB of the power supply using two Spade terminals connected to slots.


In the APFC section we find installed two capacitors manufactured by Nippon Chemi-Con with the following spec: 330μF/400V, next to it there is placed the APFC converter which uses two Infineon IPP50R140CP FET-type transistors which are manufactured by Infineon and a SCS110AG diode.


Next to the two main capacitors, mounted on a vertical PCB there is the PFC (Power Factor Correction/Controller) NPC1654 IC manufactured by ON Semiconductor.


A secondary PCB is mounted vertically on the side of the power supply, here there are placed the Weltrend WT7527V supervisor IC, which deals with the protections of the PSU and a Dual-Voltage comparator, model AS393.


The capacitors used in the PRIME 850 W Gold 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: 8GB Crucial Ballistix Tactical
–    GPU: MSI GeForce GTX 970 Armor 2X
–    SSD: Samsung 840 EVO 120GB
–    HDD: WD 1TB Blue / Samsung SpinPoint F3 500GB
–    CPU Cooler: SilverStone Tundra TD02 with NoiseBlocker eLoop B12-PS
–    Display: AOC i2769VM
–    Case: Phanteks Enthoo Luxe White
–    OS: Windows 10 64-bit


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 (5.90.4200) 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 Prime 850W Gold is one of the best Power Supplies released this year, due to its performance and silence operation with the inclusion of the semi-passive Hybrid mode. The Prime series feature a new platform and the 80 PLUS Gold, Platinum and Titanium certifications are a statement of how good the new series really is.
Thanks to its 135mm fan which uses a Fluid Dynamic Bearing and a semi-passive Hybrid mode, the power supply is silent while not compromising the cooling of the components.
The design of the Prime 850W Gold and the overall line of power supplies is unique and refined, using vents on the sides and a two-part front grille design, which is most evident in the Titanium units due to the color difference.
The cables are flexible enough to facilitate the installation process of the system, also they are entirely black and covered in high quality sleeving almost to the end of the connectors.
In conclusion, the Seasonic Prime 850W Gold is a great choice for anyone looking for a good performing power supply, featuring a new platform and unique design that will match any system and configuration.
The Prime 850W Gold comes with 10 years of Warranty however Seasonic extended that warranty up to 12 years, showing the performance and reliability of the new Prime series and platform.


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