be quiet! Dark Power Pro 850w ATX PSU Page: 1

Be Quiet Dark Power ProEarlier this year be quiet! were kind enough to send us their 650w PSU in for testing. Being a fairly new contender in the UK PSU market, we were extremely impressed by both the look, package and performance of the unit. As a result the unit was rightfully awarded Overclock3D's Editors Choice followed by many highly acclaimed awards from other sites around the globe.

Since then be quiet! has introduced several new models to the Dark Power Pro range including the beefy 1200w version covered in our recent round-up and a slightly more affordable 850w version that we're going to be taking a look at  today. Here's what be quiet! have to say about their latest power house:

First Class Level
Dark Power Pro is the high-quality power supply for perfectionists: powerful due to its highly-developed technology and extremely high degree of efficiency - unique in terms of service and quality.

With its cable management system (23 cables), every user is ideally set up for the future. ECASO thermal technology protects the PC components from overheating and guarantees a long service life. The special be quiet! fan technology plays a decisive role in ensuring that the award-winning brand runs quietly.

Dark Power Pro is also a big winner in a small package - it fits into any standard case.

Top level convenience, top level performance, top level quietness. Dark Power Pro provides everything you expect from a first class device.

First Class Technology
· Powerful, with 850 Watt
· Top quality components
· ECASO thermal technology preserves and protects components, and controls up to 4 case fans connected to the power adapter
· Only small amount of heat development due to extremely high efficiency of up to 88%
· Exceptionally stable due to 6 12V cables assigned to the components
· Extremely quiet due to be quiet! fan technology

First Class Connectivity
· Future-proof cable management with the highest possible degree of compatibility with all mainboards and graphic cards
· 23 cable sets, of which 21 are removable
· 4 x PCIe 6+2-pin
· EPS 6-pin server board adapter
· No adapter needed. Non-interchangeable due to intelligent connection concept

First Class Service
· 3 year full guarantee and therefore 1 year more than the legal requirement
· Service hotline +49 40 736 76 86 - 44 (English speaking)
· Email Support [email protected]

At a glance, the specifications list for the Dark Power Pro 650w and 850w looks like a carbon copy barring the 200w power difference. However on closer inspection we can see that the 850w unit has been given an upgrade in the modular cabling department from 18 cables (seen on the 650w) up to 23. Part of this is thanks to the much needed increase from two PCI-E connectors up to four which is a neccessity for those of us running high-end GPU's.

+3.3V: 26A
+5V: 30A
+12V1: 20A, +12V2: 20A, +12V3: 20A, +12V4: 20A, +12V5: 20A, +12V6: 20A
-12V: 0,8A
+5VSB: 4A (peak 5A)

A quick look at the tech specs on be quiet!'s website reveals the distribution of power around the unit. As we can see from above the unit features a total of six +12v rails capable of delivering 20 amps each, with a maximum load across all rails of 68amps. This is an increase of 16amps over the 650w version with an extra two +12v rails splitting the load. The +3.3v and +5v rails remain the same as the 650w unit, with 26amps and 30amps respectively.

Likewise, all other specifications remain the same including the quoted 88% efficiency levels which we'll be putting to the test later on in the review.

be quiet! Dark Power Pro 850w ATX PSU Page: 2
Packaging & Appearance

The Dark Power Pro 850w features exactly the same packaging design as its 650w brother with a fairly simplistic and dark theme being used throughout. The front outer-box gives away very little information about the unit listing only the 850w output along with a GB flag and the be quiet! logo offset bottom-left.  However, don't be fooled by this minimalistic approach as be quiet! have kitted the box with a velcro flap that can be lifted to reveal a list of features along with a plastic window that gives a teasing glimpse of the PSU's 120mm gold fan grill.

Be Quiet 850w Box Front Be Quiet 850w Box Front Flap

Be Quiet 850w Box Back Be Quiet 850w Box Open

Around the back of the packaging is an extensive list of specifications including details of the unit in a total of four languages, a power output chart and a diagram that details the length of each modular cable included in the box. Below this we are also provided with a picture of the unit from two angles and a string of award logo's from various international tech websites.

Be Quiet 850w Accessories Box Be Quiet 850w Cable Boxes

Moving on to the contents inner-box, we can see that be quiet! has managed to keep things extremely tidy, using three small accessory boxes to keep sharp objects such as mains plugs separate from the PSU. However, while it would certainly take one hell of a rough delivery to cause any damage to the Dark Power Pro, I can't help but feel that the unit should have maybe been placed inside a clear plastic bag to prevent any hairline scratches. Included in the boxes are the following items:
21x Modular cables
7x Velcro cable ties
4x Black thumbscrews
4x ATX Screws
1x Mains power cable

Be Quiet 850w Rear Be Quiet 850w Side

Be Quiet 850w Top Be Quiet 850w Back
Once again the Dark Power Pro 850w follows the traditions of the rest of the range with a highly reflective electroplated finish. Both sides of the unit are embossed with the be quiet! logo text and it's good to see that the specifications sticker has been placed out of sight at the bottom of the unit, rather than on one of the sides. Those of us with a keen eye will also notice that be quiet! have made a departure from the normal kettle lead style plug, instead opting for one that complies with new nordic legislations.

Around the front of the unit we can see the Dark Power Pro's modular system with a total of 15 colour coded connectors. However, as the modular system is a major selling point for the unit, let's cover it in greater detail over on the next page...

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Cables & Connectors

While most manufacturers tend to hard-wire the ATX and 4/8-Pin CPU cables into their modular PSU's, be quiet! have decided to only hard-wire the 24-Pin ATX connector. This may seem slightly strange at first, but as the unit supports both P4-12v, EPS 6-Pin and P8 (Server style) motherboard connectors it helps to cut down on additional cable clutter.

Be Quiet Modular Cable System Be Quiet Modular Cable System

To ensure that no mistakes are made during installation, each and every connector on the unit is colour coded. This combined with the physically different size of each connector should help prevent any harm coming to graphics cards and motherboards from the incorrect insertion of the PCI-E cables into the 8-Pin motherboard connector.
be quiet! 850w Cables

As mentioned over the previous page, the Dark Power Pro comes with no less than 21 modular cables. Granted that four of these are solely for powering 3-Pin style fans, but the remaining cables are all fully sleeved in black mesh and have reasonable lengths to ensure there are no fitting issues in full-tower cases. A full list of the included cables can be seen below:
1 x cable for peripherals 600+150+150+150+150mm ( 2xSATA / 2xHDD / 1xFDD )
2 x cable for peripherals 600+150+150+150mm ( 4 x HDD )
1 x cable for peripherals 600+150+150+150mm ( 3 x HDD / 1xFDD )
2 x cable for SATA connector 600+100+100+100mm (4 x SATA) include 3.3V
4 x cable for PCIe connector 600mm with 8pin to 6+2pin
1 x cable for P8 connector ( 8 pins ) 600mm
1 x cable for P4 connector ( 4pin ) 600mm
1 x cable for Motherboard ( Molex 4pin ) 600mm
1 x cable for mainbord ( Dualboard ) EPS 6pin 600mm
4 x cable for case fans ( controlled by PSU ) 700mm ( 1 x Molex / 1 x 3pin )
1 x cable for peripherals 500mm ( 1x HDD )
2 x cable for SATA 500mm ( 1 x SATA )
be quiet! 850w cables be quiet! 850w cables

The latest graphics cards are well supported on the Dark Power Pro, with the unit providing four 8-Pin PCI-E cables . As we can see from the image above (top-right) two of these connectors can also be reduced down to the "older" 6-Pin standard should you be running dual-GPU's that require one of each style connector.

Similarly, the ATX connector can also be converted from the latest 24-Pin standard down to 20-Pin for older motherboards by simply removing a 4-Pin connector block.

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Internal Components

Having already reviewed the 650w version of the Dark Power Pro it will certainly be interesting to see what has been changed inside the 850w version to provide it with an extra 200w of power. Quite often the upgrade can be as simple as slotting in a higher capacity transformer and capacitor, while other times a complete re-design of the PSU internals is necessary.

be quiet! 850w Inside be quiet! 850w internals
be quiet! 850w internals be quiet! 850w modular backplane
First up on the list of changes from the 650w Dark Power Pro is an upgrade to a higher quality CapXon 400v 680uf capacitor. This is accompanied by changes to several of the wire wound inductors and the inclusion of what looks like smaller filtering capacitors across certain areas of the modular connector backplane. Much like the 650w version, all cables entering the unit are bunched together with cable ties and cooling of the mosfets is provided by three black aluminium arched heatsinks.

be quiet! 850w Transformers be quiet! 850w Mains Filtering

The image above-left shows the two transformers (yellow blocks) within the unit. These are responsible for the conversion of mains voltage down to more manageable voltages such as 12v and 5v. Interestingly the transformers used are exactly the same as those used inside the 650w unit, possibly indicating that the 850w unit has received just a few tweaks and small changes in order to achieve the 200w higher power rating.

be quiet! Dark Power Pro 120mm Fan

The 120mm fan used inside the Dark Power PRO is manufactured by Protechnic Electric and has a model number of MGT12012LR-O25. As we can see from the specifications below, the fan is able to push a reasonable 61CFM through the PSU with a noise output of 31dBA. These figures combined with a heat based fan control should result in an extremely quiet unit.
Model: MGT12012LR-O25
Dimensions (mm): 120x120x25
Airflow (CFM): 61
Speed 1800 RPM
Noise (dBA): 31

Let's move on now and find out just how well the unit performs over on the next page...

be quiet! Dark Power Pro 850w ATX PSU Page: 5
Load Testing

To provide our readers with the most accurate results, Overclock3D uses a custom built PSU load tester on all reviews. This not only gives much more reliable results than the testing methods employed by other sites, but also allows for all current and future review results to be compared side-by-side. The following table shows the load that was applied to the Dark Power Pro 850w during testing.
  25% 50%75% 100%
 +3.3v Rail  4.3a 8.6a 12.9a 17.2a
 +5.0v Rail  4.6a 9.2a 13.8a 18.4a
 +12v Rail(s) 14a 28a 42a 56a
 Total 205.19w 410.38w 611.7w 820.76w

With 25% load applied to the Dark Power Pro 850w, both the +3.3v and +5v rails start off slightly high. However as we move to 50% and 75% load levels this evens out with the voltages coming close to their ideal values. Even with 100% load applied the voltages remain well within acceptable levels.

Each of the +12v rails sits almost bang on 12.0v under 25% load. This certainly goes to show that be quiet! don't believe in over-volting their PSU's with higher idle voltages to compensate for large amounts of 'sag' once a heavy load is applied. However, this does have an adverse effect for the Dark Power Pro when the load is placed at 100%, with +12v3 reporting a quite low voltage of 11.681v.


Efficiency tests are performed by measuring the wattage consumed by the power supply at the mains (Mains Draw) against the power consumed by the OC3D power supply stress tester (PSU Load). These results may not be 100% accurate, but have proven to be extremely close to results obtained from professional equipment.

As we can see from the chart above, the efficiency of the Dark Power Pro 850w seems to peak at around 50% load. While not exactly the 88% efficiency that be quiet! quote in the specifications for the unit, it's certainly very close and once again places the Dark Power Pro range as one of the most efficient PSU's we've ever tested.

Noise Levels

As you'd expect from a PSU with a name like be quiet!, the Dark Power Pro is extremely silent. At 25% and 50% load levels the 120mm fan spins at a very low RPM an could almost be described as inaudible unless you put your ear up close to it. At 75% load levels the fan does speed up a fair bit to combat the heat build-up inside the PSU, but even at this level the noise emmited is far from unacceptable

Finally, at 100% load the Dark Power Pro does become a fair bit more vocal and can easily be heard across the room. That's not to say the PSU is loud, because it certainly is not. However, talking about 100% load noise in an 850w PSU is a bit of a dead issue as not many people will be stressing the PSU anywhere near 100% and if they do it will more than likely be with powerful GPU's or CPU's - all of which require fairly noisy air cooling solutions.

be quiet! Dark Power Pro 850w ATX PSU Page: 6

be quiet! 850wWith its electroplated finish, excellent modular cabling system and great performance, the 850w Dark Power Pro is every bit as good as its 650w brother - and then a little more. During our testing the unit proved to be extremely quiet all the way up to 75% load and only started to make any really noticeable noise at 100%. Efficiency levels were also extremely good with the unit managing between 85-87% once a reasonable load was applied to the unit.

Voltage stability was also reasonable with the unit managing to hold extremely tight regulation all the way up to 75% load and only dipping slightly past this point. Unlike some PSU's we've tested recently, be quiet! have not heavily over-volted the rails in an attempted to make the performance look better to the casual user, but have instead just concentrated on delivering good performance from the outset. We can imagine some enthusiasts may turn their noses up at voltages dipping to 11.68v on one of the rails, but when you consider that this is only 0.20v lower than at 25% load, it puts the stability of the unit into perspective a little more.

Retailing for around £130 over at Ebuyer.Com the Dark Power Pro 850w comes in at a reasonable price point, positioning the unit between the likes of likes of Cooler Master, Enermax and Antec.

The Good
• Ultra-high efficiency @ almost 87%.
• Stable voltages with little "over-volting".
• Sexy electroplated finish.
• Lives up to its 'quiet' name.
• Excellent modular cable system.
• Package and accessories
• Price much more acceptable than it's 650w brother.

The Mediocre
• Slightly low +12v rail, but still within acceptable range.

The Bad
• Nowt

OC3D Editors Choice Award

Thanks to be quiet! for providing the Dark Power Pro 850w for review. Discuss this review in our forums.