Introduction

be quiet! is a German company that is slowly making their way into the North American market. As its name suggests (and yes, the correct spelling is all lowercase), the company specializes in creating low-noise components for PCs, mainly cooling and power related. We had the chance to see some of their new products, including their first case, at CES. The last of their products that we reviewed was the Power Zone 850W power supply, which was a bit disappointing in that it was unable to catch up with the competition and not quite quiet under heavy loads.

Our review did not phase the company, who sent us samples of their best PSU series, the Dark Power Pro, for another review. This series is strictly aimed towards enthusiasts and advanced users, seeking the very best parts available for their systems. It consists of six units, ranging from 550W up to 1200W. be quiet! supplied us with samples of their 650W and 850W models, as their reasonable power output makes them the "best sellers" of the series. However, there are large variations between the models of the series, which can be seen from the fact that only the 850W unit is 80 Plus Platinum certified – the rest of the Dark Power Pro 10 units all have a 80 Plus Gold certification. As such, we expect the two units that we will review today to be significantly different, even though they are part of the same series.

be quiet! Dark Power Pro 10 650W Power specifications ( Rated @ 50 °C )
AC INPUT	100 – 240 VAC, 50 – 60 Hz
RAIL	+3.3V	+5V	+12V	+5Vsb	-12V
MAX OUTPUT	25A	25A	54A	3A	0.5A
	125W		648W	15W	6W
TOTAL	650W

 

be quiet! Dark Power Pro 10 850W Power specifications ( Rated @ 50 °C )
AC INPUT	100 – 240 VAC, 50 – 60 Hz
RAIL	+3.3V	+5V	+12V	+5Vsb	-12V
MAX OUTPUT	25A	25A	70A	3A	0.5A
	140W		840W	15W	6W
TOTAL	850W

Packaging and Bundle

Both Dark Power Pro 10 units share a virtually identical packaging, with the obvious differences being the power rating and the 80 Plus certification badge. It is a very professional looking, sturdy cardboard box, with thick layers of polystyrene foam offering sufficient shipping protection. Ample information on the features, specifications and even the length of the cables is printed on the back of the box.

 

be quiet! treats the Dark Power Pro 10 as the top-tier units they are supposed to be and provides a wealthy bundle with these units. Inside the box we find a manual, the typical AC power cable, five black screws, five thumbscrews, several cable ties, six quality cable straps, a jumper for the OCK mode, and a switch with an LED mounted on an expansion slot cover.

We should note that there are five screws and five thumbscrews, even though that the PSU requires four, because be quiet! offers a spare just in case one gets lost. These screws are longer than typical 3M case screws, which are not sufficiently long for the proper installation of the power supply.

Regarding the OCK mode, it is a feature that the Dark Power Pro 10 units offer, allowing the user to "merge" the four 12V lines into one. This can be done by using the provided jumper, which will lock the Dark Power Pro 10 to a single rail OCP monitoring mode, or by installing the expansion cover with the switch, allowing for on-the-fly mode changes. Obviously, the power output of the unit does not get any more powerful; OCK simply overrides the stock OCP (over current protection) configuration, ceasing the monitoring of separate 12V rails and monitoring the entire 12V line as a whole.

For safety reasons, the "single 12V rail" mode is not allowed by the ATX design guide, especially with units this powerful. That is because the OCP will not be triggered if the whole output of the unit is going through a single wire, in which case the cable or the connector can easily melt, potentially even starting a fire. However, the ever-increasing power requirements of modern equipment (especially GPUs) could cause the OCP to trigger even when the PSU itself could handle the load, which has led most high-end PSU manufacturers to ignore the safety norm and go with single 12V rail monitoring.

The cables of the Dark Power Pro 10 are all sleeved and with color-coded wires, which may be a bit too typical for a PSU of this class. It would have been good for be quiet! to at least use black wires or a more distinct sleeving. Five extra cable straps, which are simple and straight unlike those provided separately in the bundle, hold half of the cable packs together and can be repurposed after the PSU has been installed inside a case.

External Appearance

Aesthetically, the Dark Power Pro 10 stands out from the crowd. The design of both the 650W and the 850W units that we received is nearly identical, with the only noteworthy difference being the depth of the chassis – the 850W version is 190mm deep, making it 10mm longer than the 650W version. Much like the Power Zone CM PSU that we reviewed a while ago, the fan guard is not a typical circular grill but an array of parallel wires. The main visual difference is that the Power Zone CM did not have decorative stickers covering the sides of the chassis.

There is a plastic frame at the back of the unit, adding a spacing between the case and the PSU for vibration absorption purposes. A rubber strip surrounds the front of the unit for the same reason. be quiet! installed an aluminum plate cover at the front of the unit, with a flexible rubber gasket covering the square hole of the only cable hardwired to the body of the unit. The sticker with the electrical specifications is on the top side of the chassis.

These enhancements however add bulk, making the 850W version of the Dark Power Pro 10 180mm deep, significantly deeper than a typical ATX PSU. The plastic frame at the front of the unit also pushes the opening of the cooling fan slightly backwards, even if only slightly. This could lead to the partial blocking of the opening by the case if the intake opening of the PSU compartment is not large enough, as many low-cost cases has openings barely large enough for the 120mm fan of an ATX-compliant (140mm) chassis. Users should ensure that their case can accommodate a PSU this long before buying.

Internal Design

Although both units are nearly identical visually, the 650W and 850W versions of the Dark Power Pro 10 are entirely different on the inside. That is true even for the cooling fan. Both units are using be quiet!'s own SilentWings P10 fans, but the T13525-HF18 and the T13525-XF20 are installed in the 650W and the 850W versions, respectively. Both fans utilize a fluid dynamic bearing, the same number of blades, and the same ribbed SilentWings fan design. The main difference is in their maximum current draw and, by extention, their maximum fan speed, though the difference is only 200RPM.

 

The cooling fans of the Dark Power Pro 10 650W (left) and 850W (right)

The Dark Power Pro 10 650W unit is based on an FSP (Fortron-Source) design. FSP is an OEM known for their good mainstream units but they are not really a supplier most companies prefer to use for their flagship series. be quiet! used the same OEM for their Power Zone CM series and that did not turn out so well. The Dark Power Pro 10 650W unit however is based on a more modern and efficient design. We found an acceptable filtering stage, comprised of four Y capacitors, two X capacitors, two filtering inductors, and a metal oxide varistor (MOV).

The presence of the MOV was a bit of a surprise – MOV's are commonly used for surge suppression but FSP rarely installs them into their units, declaring that the APFC stage is sufficient for this task. Two Matsushita 270μF/450V capacitors are present in the APFC stage, while the secondary capacitors are supplied by Nippon Chemi-Con and Rubycon (electrolytics), and CapXon (polymer).

From a technology perspective, the Dark Power Pro 10 650W unit is not very complex, with two transistors forming a half-bridge inversion stage and four transistors the secondary stage conversion stage, generating the 12V DC line. The 3.3V and 5V lines are derived from DC-to-DC conversion circuits present on the vertical daughterboard.

The 850W version is an entirely different story (and design). It is the only unit of the series with a core design coming from Seasonic, with be quiet! performing some modifications to match the features and visual appearance of the Dark Power Pro 10 series. The main modifications are the insertion of the OCK capability, the hardwiring of the 24-pin ATX cable, and the replacement of the fan.

The 850W model also has a stronger filtering stage, with a line filter on the AC receptacle and additional components on the main PCB. The entire filtering stage is comprised of six Y capacitors, two X capacitors, three filtering inductors, and a MOV. There are two primary conversion bridges bolted onto their dedicated heatsink. The blue 390μF/420V APFC stage capacitors are supplied by Hitachi, while all of the smaller capacitors, electrolytic and polymer alike, are supplied by Nippon Chemi-Con.

Four transistors form a full-bridge LLC primary inversion stage. The secondary conversion transistors are not mounted on the silver heatsinks but on the rear of the main PCB, partially cooled by indirect conduction via the PCB to the silver heatsinks and by the chassis itself acting as a huge heatsink for their cooling. Again, the 3.3V and 5V lines are derived from DC-to-DC conversion circuits, which this time are present on the PCB with the modular connectors. The PCI Express connectors are not present on this PCB and are installed on the main PCB, reducing the power that needs to be transferred between the main and secondary PCBs.

Dark Power Pro 10 650W Cold Test Results

For the testing of PSUs, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M  40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox, and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs – 2014 Pipeline post.

Considering its 80 Plus Gold certification, the performance of the Dark Power Pro 10 650W unit at room temperature is good yet not extraordinary. The average conversion efficiency of the power supply within the nominal load range (20% to 100%) is 90.9%, peaking at 92.3% at 50% load, meeting its 80 Plus Gold certification. It is however worth noting that the efficiency of this PSU plummets when the load is lower than 80 Watts. All PSUs generally are inefficient if the load is below 20% of their rated capacity, but the Dark Power Pro 10 650W is less efficient than most similar products, with its efficiency taking a dive down to 72.5% at 5% load.

The Dark Power Pro 10 650W is well balanced between cooling performance and acoustics. The SilentWings fan remains quiet at low to medium loads and becomes clearly audible only if the load is greater than 300 Watts. After that point, each increase of the load sacrifices some acoustic comfort, as the fan will gradually speed up in order to cope with the increasing cooling demands.

Dark Power Pro 10 650W Hot Test Results

From the tables below, it can be seen that the output power quality of the be quiet! Dark Power Pro 10 650W PSU is average. FSP designs do not usually excel when it comes to power quality and this is no exception, with the voltage ripple on the 12V line going up to 68mV when the unit is fully loaded. If the PSU is heavily cross-loaded, the ripple increases even further. These figures are well within the 120mV limit of the ATX design guide but certainly not impressive for a flagship series product. The voltage regulation on all of the lines is about 2.5%, a good but unremarkable figure.

Main Output
Load (Watts)	132.35 W		328.7 W		486.47 W		645.37 W
Load (Percent)	20.36%		50.57%		74.84%		99.29%
Line	Amperes	Volts	Amperes	Volts	Amperes	Volts	Amperes	Volts
3.3 V	3.8	3.37	9.5	3.34	14.25	3.3	18.99	3.28
5 V	3.8	5.08	9.5	5.05	14.25	4.97	18.99	4.95
12 V	8.21	12.21	20.51	12.14	30.77	11.98	41.03	11.92

 

Line	Regulation (20% to 100% load)	Voltage Ripple (mV)
		20% Load	50% Load	75% Load	100% Load	CL1 12V	CL2 3.3V + 5V
3.3V	2.6%	12	18	20	26	16	28
5V	2.6%	16	20	24	30	16	32
12V	2.4%	22	36	50	68	74	30

High ambient temperatures have an impact on the energy conversion efficiency of the be quiet! Dark Power Pro 10 650W PSU, but not overly so. The average nominal load (20-100%) efficiency is reduced down to 90.1%, a justifiable drop of 0.8% for an ambient temperature increase of about 22°C. Again, the efficiency peaks at 50% load, but at 91.4% this time, presenting a 0.9% drop.

Due to the higher temperatures, this time the cooling system of the Dark Power Pro 10 650W PSU behaves more aggressively, speeding up the fan even at lower loads. The PSU does maintain reasonably comfortable acoustic levels with a load up to 350 Watts, beyond which point the fan has to increase its speed in order to counter the increasing energy losses. At heavy loads and with an ambient temperature of over 45°C, the Dark Power Pro 10 650W unit is clearly audible but not overly so, while the cooling system manages to maintain good internal temperatures. 

Dark Power Pro 10 850W Cold Test Results

Again, for the testing of PSUs, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M  40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox, and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs – 2014 Pipeline post.

Being an 80 Plus Platinum certified unit, it is not surprising that the Dark Power Pro 10 850W PSU delivers excellent electrical performance. The average conversion efficiency of the unit within the nominal load range (20% to 100%) is 92.8%, surpassing even the peak efficiency of the less powerful 650W version, while this time the efficiency peaks at 94.5% at 50% load. It performs fairly well under very low loads too, maintaining acceptable efficiency levels with a load down to 60 Watts. With a load of just 5%, the efficiency drops down to 76.9%.

Considering its power output, the Dark Power Pro 10 850W balances thermal performance and acoustics almost perfectly. The cooling fan remains inaudible with a load up to about 400 Watts, at which point it will speed up in parallel with the load to meet with the increasing thermal losses. Even with the PSU at maximum stress however, the SPL levels do not exceed 40.4dB(A), which is a fairly comfortable level for common home and office environments. Considering what sort of components are needed to get up to such a load (e.g. high performance GPUs and a fast CPU), the PSU noise will likely be dwarfed by the noise of the rest of the system.

Dark Power Pro 10 850W Hot Test Results

The tables below depict the superiority of the be quiet! Dark Power Pro 10 850W PSU compared to the 650W version of the same series. The output power quality is exceptional, with the maximum voltage ripple recorded on the 12V line being just 20mV with the unit running at maximum capacity – less than a third of the ripple we recorded with the 650W version at a lower power output. Cross-loading does not affect the power quality significantly either. Voltage regulation on the 12V line is at just 0.9%, but the minor lines are less tightly regulated, at 1.6% and 1.7% for the 3.3V and 5V lines respectively.

Main Output
Load (Watts)	171.83 W		428.51 W		638.14 W		849.97 W
Load (Percent)	20.22%		50.41%		75.08%		100%
Line	Amperes	Volts	Amperes	Volts	Amperes	Volts	Amperes	Volts
3.3 V	4.06	3.35	10.14	3.34	15.21	3.32	20.29	3.3
5 V	4.06	5.06	10.14	5.03	15.21	4.97	20.29	4.97
12 V	11.36	12.12	28.4	12.1	42.6	12.02	56.8	12.01

 

Line	Regulation (20% to 100% load)	Voltage Ripple (mV)
		20% Load	50% Load	75% Load	100% Load	CL1 12V	CL2 3.3V + 5V
3.3V	1.6%	6	8	12	12	8	14
5V	1.7%	6	10	10	14	8	16
12V	0.9%	10	12	16	20	20	12

High ambient temperatures have virtually no impact on the electrical performance of the be quiet! Dark Power Pro 10 850W PSU. The average nominal load (20-100%) efficiency drops by just 0.2% for an ambient temperature increase of about 23°C and the peak efficiency is 94.3% at half load. These figures are well above the 80 Plus Platinum certification limits and at a far higher ambient temperature than required, as 80 Plus testing takes place with an ambient temperature of 25°C.

The high efficiency of the be quiet! Dark Power Pro 10 850W PSU allows for a less aggressive cooling profile, with the unit maintaining comfortable noise levels across most of the load range. Only if the load is greater than 700 Watts will the fan of the unit reach levels uncomfortable for continuous use; however, a computer that draws that much power is not performing a casual tasks and its cooling systems are bound to be generating significant levels of noise as well. 

Conclusion

The conclusion of a review testing two products of the same series should have been uncomplicated and straightforward. Normally, such units would share the same number of features and similar characteristics; however, the Dark Power Pro 10 series is a clear exception to that hypothesis. Besides their visual similarities, the 650W and 850W versions are nothing alike.

Both units are externally similar, sharing the same visual modifications that create a neat, high quality appearance. They are among the best-designed PSUs that we have seen to this date. On the inside however, the two units that we have tested today are entirely different. The 650W version is based on a platform from Fortron-Source (FSP), while the 850W version is a modified Seasonic XP platform. Both versions perform well enough to meet the manufacturer's specifications but the 850W unit greatly outclasses the FSP-based version on all fronts. Ironically, the Seasonic XP platform is a design that is over three years old and still has little competition when it comes to overall performance.

be quiet! is a company focused on creating low noise products and markets their flagship Dark Power Pro 10 series as the "world’s quietest PSUs in the high performance category". The "world's quietest" part is pushing it a little, but both units displayed a good balance between thermal performance and acoustics. However, the more efficient 850W version outperforms the 650W unit, being capable of running at lower temperatures and generating significantly lower noise levels, even at higher loads. Nevertheless, both of the Dark Power Pro 10 PSUs delivered well and their difference on acoustics was expected from just their power output and efficiency specifications.

When it comes to electrical performance and specifically to the output power quality, the 850W version severely outclasses the less powerful unit. The Dark Power Pro 10 650W PSU delivered good electrical performance and power quality, well within the design guide limits, yet it's not what we would consider acceptable for a flagship product with such a price tag. On the other hand, the 850W version performed much better, delivering three times better power quality, much stronger voltage regulation, and higher conversion efficiency.

As far as build quality goes, most enthusiasts would (rightfully) argue that the Seasonic-based unit should be better. After all, Seasonic does have a better reputation than FSP when it comes to quality. However, this is not the case here, as both units are on equal footing as far as the build quality goes. The soldering and assembly of either unit is excellent, without any flaws that we could find.

Moving over to the internal components, the only noteworthy difference is the presence of the CapXon polymer capacitors in the 650W version, while the 850W unit is using Japanese capacitors all around. CapXon is a fairly reputable company and their polymer capacitors are among the best worldwide, but be quiet! should be bragging about using "premier quality Japanese capacitors" only in the features list of their 850W Dark Power Pro 10 PSU.

We found the Dark Power Pro 10 650W unit retailing for $180 at the time of this review, while the 850W version can be found selling for $240. Both price tags are very steep, especially when you consider that the Seasonic XP2 860W PSU can be bought for $165. Nevertheless, the 850W unit still has some potential, especially for people that care about the appearance and the cooling fan of their units. On the other hand, the 650W version is severely overpriced and its marketing potential seems very limited, particularly for the North American market. For example, the Corsair AX760, a 760W 80 Plus Platinum PSU, currently retails for $5 less than the Dark Power Pro 10 650W. The EVGA SuperNOVA 650G1, a PSU also based on a FSP platform (albeit a different one) can be found for just $80.

Due to its unique appearance and good cooling fan, the Dark Power Pro 10 850W does have some market potential – especially in Europe where the prices of be quiet! units are lower. However, short of a massive price cut (e.g. about half the current price), there is no reasonable scenario where the Dark Power Pro 10 650W can become a financially interesting choice. It's not that the Dark Power Pro 10 650W is bad; however, it is greatly outclassed by the Dark Power Pro 10 850W and terribly overpriced to stand any hope in the North American market.