Be Quiet! Power Zone 850W PSU Review Introduction

Be Quiet! has been a very active player in the PSU market during the past few months. Not only have they released several new products and new series of units, the German company is currently on their way to "invade" the North American markets. We reviewed several of their products in the past, such as the top-tier Dark Power Pro 10 and the mainstream Pure Power L8. There is a huge gap between these two series however and Be Quiet! has released a new series of units, the Power Zone, in order to bridge it.

The Power Zone series is the "gamer" series from Be Quiet!, consisting of high performance, high quality units for those who are willing to pay more than a little extra for performance. It consists of four units, ranging from 650W to 1000W, so they are definitely designed for very strong, power-hungry systems. We are going to have a look at the 850W version of the Power Zone series today, which currently sells for $159.90. The current prices of the units available in the US are obviously in need of an update, as distribution is rather problematic for Be Quiet! at the moment, but we expect that to be fixed in the following few months.

Be Quiet! Power Zone 650W


Be Quiet! Power Zone 750W


Be Quiet! Power Zone 850W


Be Quiet! Power Zone 1000W


Power Zone 850W

Manufacturer’s features and specifications

Continuous power (W)


Peak power (W)


Form factor ATX 12VVersion


Form factor EPS 12VVersion


Modular cable management


Special technology

Active Clamp + SR, DC/DC

Voltage (Vac)

100 - 240

Frequency (Hz)

50 - 60

Input current (A)

10 - 5



Power factor at 100% load


Compliant to Intel Haswell C6/C7


Compliant to Intel C6 mode


Power consumption in standby (W)


Average life time (h / 25°C)


Operating temperature up to (°C)




+3.3V (A)


+5V (A)


+12V1 (A)


-12V (A)


+5Vsb (A)


Max. combined current 12V (A)


Max. combined power 12V (W)


Max. combined power 3,3V + 5V (W)


Hold-up time (ms)



Packaging and bundle

The box

We received the Power Zone 850W unit inside a sturdy cardboard box with a dark, simple artwork theme. The capacity of the unit is printed with large, bold letters on the front side of the box. Inside the large box, the power supply is very carefully packed and sandwiched between thick packaging foam.

The box (rear)

The most important features and specifications of the unit have been printed on the rear side of the box, in English and German. Although the box looks like a small manual, there is even more information about the unit in the company's website.

 Bundle and cables

Aside from the unit itself, inside the box we also found a typical A/C cable, a well-written manual, five black 3M screws, a few basic cable ties and four packs of modular cables. The modular cables are wrapped in black sleeving with a dark orange decorative trace. Each pack is held together by a reusable cable strap.

The exterior of the Power Zone 850W PSU

 Power Zone 850W

 In terms of appearance, the Power Zone 850W unit certainly is unique. Be Quiet! obviously spent a lot of time and effort on the appearance of their product. Much like the Dark Power Pro 10 series, the Power Zone sports a proprietary fan cover, which has a distinctive design of parallel wires. Be Quiet! also installed a soft plastic frame at the front of the power supply and a rubber strip surrounds the rear of the chassis, both in order to limit metal-to-metal contact and absorb vibrations. Note that the non-standard chassis is several centimeters longer than typical ATX designs, measuring 7.5 inches deep, which could be a problem with small and HTPC cases.


The sides of the Power Zone are certainly unique as well, with the artwork that we saw on the box being recreated as an embossed design on each side of the unit. A simple sticker with the unit's series printed on it can be seen in the middle.

 Top side

The sticker with the electrical specifications of this power supply can be found at the top of the chassis. This sticker will only be readable from the outside of a windowed computer case if the PSU has been installed below the motherboard tray and the view to the PSU compartment is unobstructed.

 Front Side

The plastic frame of the Power Zone differentiates the front side of the unit from the majority of the power supplies available. A sticker with the company logo can be seen next to the A/C receptacle. The company logo is also embossed on the top side of the plastic frame.

 Rear Side

The plastic frame on the rear side of the Power Zone is littered with connectors for the modular cables. There are fourteen connectors; three for the fan power cables, three for the PCIe cables, two for the CPU 12V cable, four for the SATA and Molex cables and finally two for the ATX cable.

The interior of the Power Zone 850W PSU

 Silent Wings Fan

Be Quiet! has their own series of fans, the Silent Wings, which they are also using in their PSUs. The Power Zone is no exception. A Silent Wings fan of similar specifications as the higher end models can be found in the Power Zone, using the same FDB (self-lubricating bearing) and ribbed blades as the fans found in the Dark Power Pro 10 series. The only difference is that this fan is much stronger, with a maximum speed of 2900RPM.

 Inside Pic

Be Quiet! entrusted their Power Zone series to the same OEM building their medium power Dark Power Pro 10 units, Fortron-Source (also known as FSP). Fortron-Source is a known OEM of mainstream PSUs but they have very few high power designs. Although Be Quiet! advertises that this unit sports quite a few high-tech features, such as an Active Clamp and DC to DC converters, the Power Zone only has an 80Plus Bronze certification. This actually may be the first unit that we have ever seen to come with DC to DC conversion and unable of at least 80Plus Silver levels.

 Filtering Stage

The filtering stage begins on the back of the AC receptacle and continues on the main PCB. The total number of components sum up to four Y capacitors, two X capacitors and two filtering chokes, which are enough for a good filtering stage. The first rectification stage begins from two bridges, sandwiched together onto a stand-alone heatsink right next to the filtering stage.

 Primary Side

The active components of the APFC stage, two transistors and a diode, have been placed on their own heatsink at the edge of the unit. The passive APFC components are a large coil and two Teapo 220 μF / 450 V capacitors. Then the primary inversion stage begins on the smaller heatsink next to the primary transformer, which holds three transistors, forming the active clamp reset forward topology.

 Secondary Side

The secondary conversion stage starts right after the main transformer, with four transistors. Only a 12V line is generated and the 3.3V/5V lines are derived via DC to DC circuits. There is a mix of electrolytic and solid-state capacitors, with the electrolytics supplied by Teapo.

 Test setup

The load

In order to be able to effectively and efficiently test any computer power supply unit, we developed and constructed our own proprietary testing station. Our testing station consists of a number of power resistors and small capacitors, which in turn are connected to a RS485 electronic relay array which allow our load to be controlled through computer software alone.

USB interface and connection panel

When accuracy and speed are of critical importance, a simple multimeter or voltage meter is not sufficient for the task. To ensure the quality of our testing, an USB laboratory interface is being used to continuously monitor and record the readings of all voltage lines simultaneously. For ripple measurements, an oscilloscope is necessary and we chose the USB Instruments Stingray, the most widely used oscilloscope amongst low voltage PSU engineers and testers.

Measurement instruments

For accurate testing and repeatable results, a stable power input is also required. Thus, we are providing power to our test samples through a 3kVA VARIAC which allows us to control the input voltage of our test samples and also perform efficiency tests under both 110V AC and 230V AC input. A Lutron DW-6091 is also being used, monitoring the input voltage, real and apparent power, power factor and amperage.

The software

A power supply testing procedure would not be complete without thermal and acoustics tests. For our acoustics tests we are using a SL-5868P digital sound level meter, placed 1 meter away from the unit (DIN standard). Two PT100 sensors and their respective displays are being used to monitor the ambient temperature and the exhaust temperature of the unit.

Complete test setup during trial run


Testing results (Regulation & Ripple)


V3 V5 V12

The electrical performance of the Be Quiet! Power Zone 850W power supply is good; not excellent but not bad either, considering the class of the power supply. Voltage regulation is at 2.2% on the 12V line and, slightly higher, at 2.6% on the 3.3V/5V lines, which are very good figures even for high performance units. Ripple suppression however could have been better. Even though the figures were much lower than the 120mV limit on the 12V line and 50mV limit on the 3.3V/5V lines, there are many high performance power supply designs can do much better than that.

Testing results (Efficiency, Noise & Thermal)


As we mentioned before, the Power Zone 850W comes with an 80Plus Bronze efficiency certification, despite the several advanced features. The unit certainly managed to meet its expected efficiency, reaching up to 89% at 50% load, a figure which could have granted it 80Plus Silver status if the efficiency would not drop so sharply at low and high loads. The difference between 20% or 100% and 50% load is a whooping 6%, which is massive for any power supply, let alone a high performance one, and is what prevented the Power Zone 850W unit from receiving a better certification.


The Power Zone 850W has a good acoustic profile, for an 850W unit with an 80Plus Bronze certification at least. While lightly loaded, the Power Zone 850W is running very quiet. This gradually changes above 50% load though, as the fan will start speeding up in order to cope with the increasing heat generation. If the load is higher than 600W, the Power Zone is clearly audible from a distance of 1 meter.


The thermal performance of the Be Quiet! Power Zone 850W unit is good but in no way remarkable. It is almost linear, following the increasing heat losses as the output of the PSU increases. A maximum delta of 7.2°C at maximum load is excellent for an 850W PSU with an 80Plus Bronze certification; however, this comes at the expense of the unit's acoustic performance, as the Power Zone more than a bit noisy at that point.

Be Quiet! Power Zone 850W PSU Review Conclusion

 The Power Zone is a series designed to bridge the gap between the mainstream Pure Power series and the top-tier Dark Power Pro 10 series, aiming for gamers and enthusiasts that want more than just an average PSU but not willing to pay top buck for the very best there is.

From a technical point of view, the Power Zone 850W unit is excellent. It has good electrical performance, with very good voltage regulation and acceptable ripple suppression, it is quiet when lightly loaded and runs very cool as well. The only part which disappointed us was the electrical efficiency, which does meet the 80Plus Bronze certification of the unit and then some, but we expected more from a design with all these features. When it comes to quality, we can say that things are acceptable. The power supply is very well made and the company backs it up with a five-year warranty, but we somehow think that most enthusiasts will not be thrilled to see that the primary supplier of capacitors is Teapo.


Perhaps the strongest feature of the Power Zone series is the design of the unit itself. Aesthetically, the Power Zone stands out from the units of any other brand. It is a modular unit and, even though they are simple color-coded wires, the dark orange trace on the sleeving gives them a unique look as well. If you want something that stands out, the Power Zone definitely is it.

The only real problem with the Be Quiet! Power Zone 850W power supply, and the entire series as well, is the sparse availability. These products are still not widely available into the North American markets and the few sellers that supply them do so at significantly increased price. The 850W version which we reviewed today can be found for $159.90 plus shipping, a steep price for an 80Plus Bronze certified unit. The fully modular design and the warranty help balancing the scales a little but the Power Zone 850W unit currently is going to be facing severe competition in the US.


Legit Bottom Line: Although the Power Zone 850W power supply performs well, the company primarily based their focus on reliability and appearance. It is a very good product overall but still hard to find in the US. If you can find it for a reasonable price however, it would be a very good choice for a power-hungry gaming PC.