Today we are going to look at the Be quiet! with a power of 850 W from the top Dark Power 12 line, the devices of which are distinguished by their original appearance and the 80 Plus Titanium certificate. It also includes 750- and 1000-watt solutions. The manufacturer promises a very quiet and powerful power supply with excellent performance. Let’s see if that’s the case.

Be quiet! Dark Power 12 850W

Be quiet! Dark Power 12 850W

Model Be quiet! Dark Power 12 850W
Product page P12-850W
Power, W 850
Energy Efficiency Certificate 80 Plus Titanium
Form Factor ATX
Cable Connection Diagram Modular
Channel power +12V, W (A) 840 (70)
Channel power +5V, W (A) 120 (24)
Channel power +3.3V, W (A) 79,2 (24)
Combined power +3.5V and +5V, W 120
Channel power -12, W (A) 6 (0,5)
Channel power +5Vsb, W (A) 15 (3)
Active PFC +
Mains voltage range, V 100-240V
Mains voltage frequency, Hz 50–60
Fan size, mm 135x135x25
bearing type hydrodynamic
Number of cables/connectors for CPU 2/2x EPS12V (4+4)
Number of cables/connectors for PCI-E 3/2x (6+2)
Number of cables/connectors for SATA 4/12
Number of cables/connectors for IDE 2/5
Number of cables/connectors for FDD 1/1
protection OPP, OVP, UVP, SCP, OСP, OTP
Dimensions (WxHxD), mm 150x86x150
Warranty, months 120
Price 7299 hryvnias

The block comes in a fairly large black box, on the bottom there is a plate with the technical characteristics of the device. Inside it has another smaller box that contains all the additional components, the block itself is packed in a thick form of polyethylene foam.

A power cable, a set of modular cables, a set of cable ties, a set of mounting screws, instructions, an Overclocking key bar with a switch and an indicator, a jumper with a similar function without indication were put in a small box. The last components are something unknown to ordinary users. The manufacturer claims that this is a special key that switches the power supply into a mode with one common +12 V line, while in normal mode there are four virtual lines with separate protection for each, but with much less power in order not to overload individual cables in case of emergency situations. As a result, with the “overclocking” function enabled, any individual cable can be supplied with all the power that the +12 V unit is capable of delivering, and which at the peak can add up to 20% more than the declared 840 W, so you need to be very careful with this function. On the one hand, it can help when working with top-end video cards that have large power consumption spikes, but on the other hand, there may be a situation where, if the power supply system of the video card or processor fails, a short circuit occurs and all the power of the power supply goes into the broken an element with a big firework and PCB burnout, melting of connectors and power cable. And the more powerful the power supply and the less sensitive protection, the more sad the consequences will be, and the probability of a successful repair of components will tend to zero. In the case of sensitive protection on individual lines, this may not happen, the power supply can turn off before the irreparable happens. The switch with a jumper does not affect the fan speed in any way, they only change the protection algorithm.

Be quiet! Dark Power 12 850WBe quiet! Dark Power 12 850W

Power supply with fully modular cables, their number and length are as follows:

  • one to power the motherboard (60 cm);
  • one with one 8-pin (4+4) CPU power connector (70 cm);
  • one with one 8-pin non-separable connector for processor power (70 cm);
  • three with two 8-pin (6+2) connectors for powering a PCI-E video card (60+60 cm);
  • one with four power connectors for SATA devices (60+15+15+15 cm);
  • two with three power connectors for SATA devices (60+15+15 cm);
  • one with two power connectors for SATA devices, two connectors for IDE and one connector for FDD (60+15+15+15+15 cm);
  • two with three power connectors for IDE devices (60+15+15 cm);
  • rear wall cable with switch and Overclocking key indicator (60 cm).

Be quiet! Dark Power 12 850W

The cables are made of black wire harnesses and covered with a black braid, the wires are a little stiff, the length is sufficient for large cases with a lower power supply. The power cables for video cards are double, but not like in most blocks with a branching into two 8-pin connectors at the end, but are implemented with separate wires for each connector from the block itself, into which they are connected by a common 12-pin connector. So this pair of stubs can realistically deliver up to 300W of power without much wire loss.

Be quiet! Dark Power 12 850W

The body of the block is made of steel, painted with black matte paint, on one side there is a large silver inscription Dark Power 12, on the other — a sticker with the characteristics of the block. The cooling fan is covered with a black mesh, the fan impeller is also black with a white Be quiet! in the center.

The power supply cannot be completely disassembled without damaging the appearance. Some of the screws are hidden under the back sticker on the side of the connectors, which peels off when you try to peel it off, so we decided not to spoil the appearance of the device and refuse to show pictures of the back of the board.

A separate key feature of this unit is a special silent frameless fan be quiet! Silent Wings with BQ marking SIW3-13525-HF and size 135x25mm, max speed 1800rpm and hydrodynamic bearing. The fan is mounted on three metal racks, plastic inserts are installed on the sides, which form an air duct. It works very quietly, when the unit is turned on, the turntable starts at 343 rpm and makes almost no noise. As the power increases and the components heat up, the fan speed increases to about 800 rpm, the maximum speed is limited even at rated power. Due to the high efficiency of the platform, even these revolutions are enough for normal cooling, while the noise level remains comfortable.

The manufacturer indicates the topology of the block as Active Rectifier + Full bridge + LLC + SR + DC / DC, although they forgot to write APFC before Full bridge LLC, which for some reason they divided into two elements. Here Active Rectifier is already more interesting. In ordinary, not “titanium”, blocks, diode bridge assemblies are used as a network rectifier, which, in fact, are also active elements. In this case, the active rectifier means that it is a synchronous rectifier, usually referred to as SR, but, apparently, in order to avoid confusion, they simply wrote an active rectifier, since there is another synchronous rectifier at the output of the main +12 V power converter, which they already indicated as SR. Also, DC / DC converters are made on circuits with a synchronous rectifier. In general, a synchronous rectifier is a transistor, usually a field effect, installed in place of any powerful diode and controlled by a special circuit that monitors the current through the pn junction of the transistor. Unlike a diode, which can drop from 0.6 to 1.5 volts, depending on its type and operating voltage, the losses on the transistor are minimal, which significantly reduces the heating of the rectifier and increases the efficiency of the power supply. It seems that the «titanium» certificate cannot be achieved on conventional diode assemblies. In addition to a network synchronous rectifier at the input, the block does not differ in structure from modern “golden” devices.

Be quiet! Dark Power 12 850W

A full-fledged impulse noise filter is soldered at the input of the unit, some of its components are installed on the network connector. After the filter, there is a network synchronous rectifier in the form of a small board, which is sandwiched between two nickel-plated plates. The rectified mains voltage is supplied to the APFC through a thermistor to limit the inrush current at start, after turning it on, the relay closes so that the current flows directly without losses on it. The APFC inductor is quite massive, the power components of the corrector are installed on a separate radiator next to it, a fast diode based on silicon carbide C3D06060 (600 V, 19A, 15nC) and a pair of IPA60R120P7 transistors (650 V, 26 A, 0.12 Ohm) connected in parallel are used . Smoothes the power after APFC high-voltage filter, consisting of a pair of electrolytic capacitors 470 and 330 uF voltage 420 V and an operating temperature of 105 ° C series KMZ from Nippon Chemi-Con. The total capacitance of the filter is 800 uF. On the vertical board next to the radiator, there is a control circuit for the corrector and the standby power supply, the standby power transformer and its output filters are located side by side in the corner of the board — this is a pair of capacitors with a capacity of 3300 uF 10 V at 105 ° C of the KZE series manufactured by Nippon Chemi-Con.

The power transistors of the bridge resonant LLC converter are installed on a separate radiator, four pieces of AOTF190A60 (600 V, 20 A, 0.19 Ohm) are controlled by the CM6901 controller, which is located nearby on a separate vertical board. It has a construction resistor, most likely for fine tuning the voltage along the +12 V line. A synchronous rectifier is installed at the output of this converter on the reverse side of the board, transistor cooling radiators can be seen next to the power transformer in the form of two small nickel-plated plates. The output power is filtered by a whole battery of ten 470 uF 16 V polymer capacitors. The +12 V line is further divided into four virtual ones through chokes and additionally filtered by four 2200 uF 16 V electrolytic Low ESR capacitors at 105 ° C, also from Nippon Chemi-Con . There are also many small polymer capacitors on the modular jack board itself for additional filtering, so with this total capacitance, the level of ripple will be very low.

A step-down DC / DC converter assembled on a separate board is responsible for powering the +3.3 V and +5 V lines. It has a pair of toroidal chokes and six 470 uF 16 V polymer capacitors. There are also two trim resistors, most likely also for fine-tuning the voltages along the +3.3 V and +5 V lines. On the other side of this board there are six transistors BSC0901NS (30 V, 149A 1.9 mΩ), they are controlled by the PWM controller APW7159C. A similar circuit is usually installed in all modern power supplies with DC / DC converters, although with less powerful transistors. The WT7527RA supervisor is installed on the same board, next to it there is an APW9010 controller responsible for controlling the fan speed.

Be quiet! Dark Power 12 850WBe quiet! Dark Power 12 850W

Mounting and soldering are of high quality, at least all the boards are completely washed off the flux from above.

Test Methodology

The power supply test was carried out using a linear electronic load with the following parameters: current adjustment ranges for the +3.3 V line — 0-16 A, for the +5 V line — 0-22 A, for the +12 V line — 0-60 A , the error in measuring current and voltage by the stand is about 5%, all contacts for connecting cables of the tested power supply with the same voltage are connected in parallel and loaded with the corresponding load channel. The current for each channel is smoothly regulated and it is stable regardless of the output voltage of the unit. To accurately measure voltages, mains current and temperature, a Zotek ZT102 multimeter with True RMS was used. The fan speed was measured with a Uni-T UT372 tachometer. For each power line, the required current was set, and the voltage at the load contacts was measured to take into account losses on the wires.

Test results

The first test for the load capacity of the main line + 12V, the current through the lines + 3.3V and + 5V was constant with a total load of about 120 W, the results are listed in the table.

Load current on line +12V, A Line voltage +12 V, V Load power on line +12V, W Line voltage + 5V at a current of 15 A Load power on line +5V, W Line voltage + 3.3V at a current of 13 A Load power on line +3.3V, W Total load power, W
0 12,07 0 5,05 75,7 3,34 43,4 119,1
5 12,07 60,3 5,05 75,7 3,34 43,4 179,4
10 12,07 120,7 5,05 75,7 3,34 43,4 239,8
15 12,06 180,9 5,05 75,7 3,34 43,4 300
20 12,05 241 5,04 75,6 3,34 43,4 360
25 12,04 301 5,04 75,6 3,33 43,3 419,9
30 12,02 360,6 5,04 75,6 3,33 43,3 479,5
35 12,0 420 5,04 75,6 3,33 43,3 538,9
40 11,98 479,2 5,03 75,4 3,33 43,3 597,9
45 11,96 538,2 5,03 75,4 3,33 43,3 656,2
50 11,94 597 5,03 75,4 3,32 43,2 715,6
55 11,92 655,9 5,02 75,3 3,32 43,2 774,2
60 11,9 714 5,02 75,3 3,31 43 832,3
Measurements on the contacts of the power supply
60 12,18 730,8 5,1 76,5 3,38 43,9 851,2

According to the test results, we have excellent stabilization along the +5 V and +3.3 V lines, we have normal stabilization along the +12 V line, there is a slight drawdown below 12 V, which even in this form fits into the ATX standard with a good margin. The reason for the drawdown is the voltage drop on the wires, another voltage measurement was made at the contacts of the output connectors of the power supply and the voltage values ​​\u200b\u200bare indicated in the last line of the table. According to the latest values, we see that the block raised the voltage on all lines, compensating for drops on the wires. But the compensation goes only through the motherboard power cable, the rest of the loops are not covered by feedback, and the total voltage drop across the load will depend on the number of cables used on the +12 V line. The stand did not allow a full test due to the insufficient number of connectors to use all cables along this line, so the voltage drop turned out to be a little more than it could be with a complete set of power cables, in which the unit was tested by the manufacturer.

To check the load capacity of the +5V and +3.3V lines, tests were made at a constant load of +12 V to assess their influence on each other.

Load current on the line + 3.3V, A Line voltage +3.3 V, V Load current on the line + 5V, A Line voltage +5V, V Load current on line +12V, A Line voltage +12V, V
0 3,34 0 5,07 15 12,07
0 3,34 5 5,07 15 12,07
0 3,34 10 5,06 15 12,07
0 3,34 15 5,05 15 12,06
5 3,34 0 5,07 15 12,07
10 3,33 0 5,07 15 12,07
15 3,32 0 5,07 15 12,06
15 3,32 15 5,05 15 12,05

According to the test results, we have excellent stabilization along the +3.3 V and +5 V lines, which is the norm for units with low-voltage DC/DC converters.

The unit efficiency test was carried out at a mains voltage of 230 V, the test results are listed in the table.

Load power, % Load power, W Consumed network current, A Mains voltage, V Efficiency, %
25 212 0,96 236 93,5
50 425 1,91 234 95,1
75 637 2,96 231 93,1
100 832 4,03 227 90,1

The efficiency in our test turned out to be slightly less than the requirements of the 80 Plus Titanium certificate, but you need to take into account that this is the efficiency taking into account cable losses, and not all of them were used on the +12 V line. In the test configuration of the stand, the losses on the cables only turned out to be 2.3%, which significantly affects the overall efficiency without taking into account the power supply itself, while using all the power cables along the +12 V line, the losses on the wires would be about 1.5% if not less. Well, our equipment is not quite suitable for accuracy, the error of which is only +/- 1.5%, and for a more accurate measurement, less than 1% is needed. So, here the problem is not in the block, but in the stand itself.

The heating test of the unit components was carried out at an air temperature in the room of about 21 °C. Using the Scythe Kaze Master Pro panel, sensors were installed on the main power components, and a Zotek ZT102 multimeter thermocouple was installed on the power transformer. The unit was loaded at maximum power and worked until the temperature of the power transformer stabilized. The Scythe panel readings were recorded, after which the cover with the fan was quickly removed and the temperatures of the remaining components were measured. The results are shown in the following photo:

Be quiet! Dark Power 12 850W

In general, temperatures are standard for energy-efficient units, not very low, but not critically high either. With a long maximum load in our test, the cooling fan speed increased to only 680 rpm, while the noise was low, much quieter than the rest of the bench fans. In the case, the maximum speed and noise level will be slightly higher, depending on the ventilation of the case and the temperature in the room.


Tested by Be quiet! Dark Power 12 850W turned out to be a very quiet and high-quality power supply. Thanks to excellent equipment, advanced circuitry, build quality and a fairly long warranty period, it will find its buyer, who cares about maximum silence from the assembled system. Those who are not very interested in the lowest possible noise level can easily save money and get by with the “golden” solutions from be quiet! or another eminent manufacturer, the service life and power quality will be similar. But, despite the structural similarity with them, our «titanium» has a slightly larger margin of components, which is needed not so much for greater reliability, but to obtain greater efficiency. As for the Overclocking key, it is better to use this function when absolutely necessary, when you need to power a modern powerful video card, but it was not possible to choose a combination of cables that correspond to one or another +12 V line. Or use during overclocking events.

original design

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