en ru ua


logo minifile

::>Power supplies > 2014 > 04 > Seasonic M12II-850 Bronze Evo Edition (SS-850AM2)

Print version
Republish review



Seasonic M12II-850 Bronze Evo Edition  PSU review

This year Sea Sonic Electronics Company has launched a new series of Seasonic S12G power supply units and updated Seasonic M12II Bronze line. Its lineup was added by four devices with capacity of 520, 620, 750 and 850W. The new items were named: Seasonic M12II-520/620/750/850 Bronze Evo Edition and probably will replace their Seasonic M12II 520/620/750/850 Bronze. However, we don’t know when this idea will be realized. Also, there are no reliable data about the cost of new devices at CIS.

Power unit Seasonic M12II Bronze Evo Edition is aimed to the mass market segment.

Seasonic M12II-850 Bronze Evo Edition

The first model we are going to introduce is   Seasonic M12II-850 Bronze Evo Edition, which in pricelist of computer shops can be found by index Seasonic SS-850AM2.

The specs:


Sea Sonic Electronics


Seasonic M12II-850 Bronze Evo Edition




Nominal capacity, W


12V power, W


+3,3V & +5V combined, W


Number of +12V lines


Outputs, А









+5VSB (extra power supply line)


PCIe- connector

6 (6+2-pin)

SLI Ready


CrossFire Certified




Efficiency, %

81 - 85

80 PLUS Certified


Power factor , %

Up to 99

Method of Power Factor balancing


Input power, W

100 - 240

Frequency, Hz

50 - 60

Input current, А

12 - 6

Fan size, mm

120 х 120 х 25

Fan speed controller

Yes (S2FC)

Noise level, dB

Up to 43,3





Compliance of RoHS (low content in the solder of lead and cadmium)


Dimension, mm

170 х 150 х 86


The bundle includes a regional specific power cable, cable bag, installation screws, user manual, case sticker

Warranty, years


Producer’s website

Sea Sonic Electronics

Packing, bundle and design

Seasonic M12II-850 Bronze Evo Edition

PSU Seasonic M12II- 850 Bronze Evo Edition is shipped in cardboard box which provides protection against impact and possible mechanical damages. Despite the officially new name of the series the packaging design was not changed. It still framed in orange and black colors, characteristic line PSUs Seasonic M12II Bronze. The same orange–black colors are adopted for this design.

The face of the box contains the key features: nominal capacity (850W) and energy efficiency class (80 PLUS Bronze). Also here are stickers specifying the information that Seasonic M12II- 850 Bronze Evo Edition has support of Multi-GPU technologies, device corresponds modern standards of energy saving and the requirements of Intel Haswell processors. Sticker with the inscription «E-CAP 105°C Japan» directly statements to the usage of the high-quality circuitry.

Seasonic M12II-850 Bronze Evo Edition

The reverse side provides the list of key features for this model. In our opinion the most useful and important are the following: DC to DC converter design and presence of fully modular cables. Sea Sonic Electronics Company approves other less expensive models and we agree with this opinion.    

As is well known the indirect measure of power unit quality is period of warranty. For this model it is 5 year, i.e. is among “gold” representatives of Seasonic G and Seasonic S12G series.

Seasonic M12II-850 Bronze Evo Edition

Delivery set includes the following components:

  • power cable;
  • set of modular cables in special bag;
  • installation screws;
  • logo sticker;
  • user manual.

The box contains all important items that may be required during the installation and connection of the power supply. A set of modular cables is not shown in the photo, and we will deal little bit letter.

Seasonic M12II-850 Bronze Evo Edition

According outward design this model is similar to other retail-solutions of Seasonic brand. It has the same trendy case with stamped grate instead of grill. Also vents are on the front wall along with mains socket and power button.

Seasonic M12II-850 Bronze Evo Edition

Hovewer main design changes of Seasonic M12II-850 Bronze Evo Edition in comparison with Seasonic M12II-850 Bronze are connected with backboard. Instead of half-modular configuration here you will see full modular cable design. It means, all cables are detachable even those which are used for power of motherboard and CPU. Earlier this feature was available only for top models of Sesonic X and Seasonic Platinum series.

Total number of sockets on backboard is ten. All of them are signed and have different configuration, so even unskilled user will cope with connection actions. 

Seasonic M12II-850 Bronze Evo Edition

Seasonic M12II-850 Bronze Evo Edition

Main 20+4-pin power socket ATX is unassembled. Two connectors of ATX12V: 4+4pin and 8-pin are provided for additional CPU power supply.  Graphics card power supply is realized via six 6+2-pin sockets, this will allow to connect three high-level graphics adapter without the usage of off-side adapter. In other words, Seasonic M12II-850 Bronze Evo Edition model is suitable for high-performance gamer systems. Other connectors are enough. And its layout on various length cables will allow you to connect the device inside the computer without problems. All cables have easy-to-use flat ribbon style.

All available socket types as well as cable length are given in the following table:

Socket type


Cable length up to socket, cm

Modular (detachable) cables

ATX 20+4-pin socket



ATX12V1 4+4-pin socket



ATX12V2 8-pin socket



2xPCIe 6+2-pin sockets



3xPATA sockets



2xPATA sockets



4xSATA sockets



2xSATA soxkets



Adapter from PATA to FDD



Seasonic M12II-850 Bronze Evo Edition

One side wall includes a sticker with technical parameters. +12V channel capacity is 840W that corresponds nominal capacity of the unit. As for many high-quality solutions with high efficiency, +12V channel is realized as one line and is not divided for several “virtual”. At the same time it is designed for very high load of 70A. This is very important feature for high-performance systems with several graphics cards.

+3,3V and +5V lines have total power capacity of 150W and each can take a load of 25A. This value will be enough for modern components.

According energy efficiency Seasonic M12II-850 Bronze Evo Edition model corresponds 80 PLUS Bronze standard. Let’s remind that power supply units are standardized to 80 PLUS Bronze if their efficiency for voltage 230V at loads 20%, 50% and 100% is not lower 81%, 85% and 81% respectively.

Also we want to specify a wide range of input voltages from 100 to 240V that allows to reject from external voltage stabilizer in case of network instability.

Internal device

Seasonic M12II-850 Bronze Evo Edition

Disassembling process is quite clear and simple. The only thing you need to do is to unscrew four installation screws out top panel. Pay your attention to the presence of special sticker “Warranty void if removed”.

Seasonic M12II-850 Bronze Evo Edition

120mm 7 blade ball bearing fan ADDA AD1212UB-A70GL is used to cool inside components. The letter “U” and sign 0,5 А confirm that this is the most powered model among  ADDA AD1212xx-A70GL model. Detailed specification is given in the following table:



Bearing type

Rolling bearing

Supply voltage, V


Current, А


Power, W


Max speed of rotation, rpm


Air flow, CFM


Noise level, dB

Up to 43,3

Dimensions, mm


There is a special small pellucid plastic plate fixed to fan with the aim to provide airflow optimization inside the power unit.

Seasonic M12II-850 Bronze Evo Edition

Seasonic M12II-850 Bronze PSU

Seasonic M12II-850 Bronze Evo Edition

 Seasonic M12II-850 Bronze Evo Edition PSU



From technical point of view these photos demonstrate that there is not a great difference between Seasonic AM2 (Seasonic M12II-850 Bronze Evo Edition) and и Seasonic AM (Seasonic M12II-850 Bronze). Actual modernization affected only to low-voltage part in area of power output lines. But to be 100% sure let’s examine main joints of present solution more detail. 

Seasonic M12II-850 Bronze Evo Edition



Let’s start from high voltage circuits with EMI-filter used for smoothing of high-frequency noises provided by power unit. This is a standard joint for high-quality models so we are very interested in a set of used elements. The producer had provided: six Y and three X-capacitors, three ferrite coils and varistor (part is placed on a small circuit board near power socket). A great attention is given to screening and isolation of separate filter components.

Seasonic M12II-850 Bronze Evo Edition

Input rectifier consists of two diode blocks GBU806 with capacity of 8A. They are equipped with aluminum cooler. Next to them you will find big choke of automatic phase and frequency control and its power unit.

Seasonic M12II-850 Bronze Evo Edition

Behind APFC module there are two electrolytic capacitors of Japanese company Nippon Chemi-Con which have parallel connection. Each has capacity 330 µF and designed to voltage 420V and operating temperature up to 105°С. Total capacitance of the present joint is 660 µF which it an excellent value for device with 850W.

Seasonic M12II-850 Bronze Evo Edition

Seasonic SS-850AM2 uses double-ended forward converter. A big cooler in the center of board is used for cooling. APFC and converter operation is controlled by PWM controller Champion CM6802

Seasonic M12II-850 Bronze Evo Edition

Stand-by power unit (+5Vsb) is based on Infineon ICE2QR4765 chip.

Seasonic M12II-850 Bronze Evo Edition

Low-voltage part has the standard principle: input includes one powerful +12V line, and from it there are another voltages (+3,3V и +5V) using DC-DC converters. This allows you to get the maximum capacity of +12V channel. Also such layout provides separate voltage stabilization.

There are six diode blocks SBR30A50CT on +12V line. They have higher heat release in comparison with transistors. 

Seasonic M12II-850 Bronze Evo Edition

The elements of DC-DC voltage converters +3.3V and +5V are placed on daughter board. Whole power part is on reverse side of the board and covered by aluminum plate, so we could examine neither marking nor transistor quantity.  The face side has LC-filters for +3,3V and +5V channels.

Seasonic M12II-850 Bronze Evo Edition

Seasonic M12II-850 Bronze Evo Edition

For output voltage filtration the capacitors with liquid electrolyte are used. The producer is well-known Japanese Company United Chemi-Con and the elements refer to high-temperature series (up to 105°С). All this informs about good quality and durability.

Seasonic M12II-850 Bronze Evo Edition

Several additional smoothing capacitors (1000µF x 16V) are on plate with modular sockets.

Seasonic M12II-850 Bronze Evo Edition

According technical specification Seasonic M12II-850 Bronze Evo Edition power supply unit has a number of protections (OVP / UVP / OPP / SCP / OCP / OTP), including overload and overheating protection. The joint is based on popular chip PS223 and realized on separate circuit board.

Seasonic M12II-850 Bronze Evo Edition

Soldering quality is always perfect. All lines are straight and sags and other defects were not found out.

Социальные комментарии Cackle
Site Search
facebook vk YouTube
google+ twitter rss