be quiet! Dark Power Pro 11 850W PSU Review

1. Introduction2. be quiet! Dark Power Pro 11 850W (Bundle & Cables)3. be quiet! Dark Power Pro 11 850W (External)4. be quiet! Dark Power Pro 11 850W (Internal)5. Super High Res Gallery6. Testing Methodology7. Closing Thoughts8. View All Pages

be quiet! have earned a solid reputation over the years with the enthusiast audience. Their range of cases, CPU coolers and power supplies have consistently scored well on KitGuru – and today we look at one of their latest power supplies, the Dark Power Pro 11. This month they have 850W, 1000W and 1200W models launching, with lower wattage units hitting retail later. How good are these high end designs?

be quiet! plan on releasing 550w, 650w and 750w supplies in August, however current pricing for the higher wattage models are:

– Dark Power Pro 11 850 W: 199 USD, 161 GBP, 255 Euro.
– Dark Power Pro 11 1000 W: 239 USD, 186 GBP, 259 Euro.
– Dark Power Pro 11 1200 W: 279 USD, 207 GBP, 289 Euro.

All of these supplies are modular designs and feature 80 Plus Platinum efficiency. They are sophisticated Full Bridge conversion implementations with LLC and synchronous rectifying as well as DC-to-DC transformation. be quiet! also supply an ‘overclocking key' allowing the end user switch between the default four rail setting, to a single 12V rail mode.

Dark Power Pro 11 Overview:

• be quiet! SilentWings 3 (135mm) fan.
• 80 Plus Platinum certification.
• Topology: Full Bridge + LLC + SR + DC/DC.
• Overclocking Key.

be quiet! have been using similar artwork now for many years – it is immediately recognisable and includes a high resolution image of the product on the front of the box. Capacity is listed under the image, which in this case is 850 watts.

The rear of the box highlights details on the cabling configuration of the power supply. We will go into more detail on this shortly.

The primary box is basically split into two sections. The left side holds all the cables and accessories. The right side has the power supply sandwiched between two thick bits of foam.

be quiet! include felt and plastic cable ties, along with screws and external fan headers. The overclocking key allows the end user to switch between single and multi rail 12V mode. They also supply an overclocking jumper in the bundle.

No shortage of PCIe cables – 6 paired up on three cables, with another on a single cable.

The be quiet! Dark Power Pro 11 850W supply is very nicely finished, painted black and ideal to fit into any rig. The paint work is very resistant to scratching and the unit passed our ‘screwdriver' test with flying colours.

This involves running the head of a Philips head driver down the side of the chassis with light to medium force. After all, how many times have you accidentally connected with a power supply during a system build?

The large SilentWings 3 fan is hidden behind a metal grille at the top of the case. be quiet! claim this fan is based around a 6 pole motor with redesigned bearings. Noise levels are minimal and it has the lowest start up speed on the market – under 250 rotations per minute.

One side of the power supply has a power header, power switch and honeycomb vent for air flow.

This is not a ‘pure' modular power supply – a single ATX cable emerges from the right of the case. This cable is always used in a system build, so not really a problem. Along the left of the modular panel are a series of fan headers (to directly control fans inside a case), alongside the OCK header (allowing the user to switch between single and multi rail configurations).

A vertical row of peripheral headers are positioned in the center, alongside 5 PCIe headers and a single P8/P4 connector.

be quiet! Dark Power Pro 11 850W
DC Output	+5V	+3.3V	+12V1	+12V2	+12V3	+12V4	-12V	+5Vsb
Max Output	25A	25A	30A	30A	35A	35A	0.5A	3A
Max Combined Wattage	140W		70A/ 840W _______________ Total 850W				6W	15W

The be quiet! Dark Power Pro 11 850W is a capable unit, and the +12V rails are strong, delivering a total of 70A.
be quiet! are using one of their own 135mm SilentWings 3 fans, with a funnel shaped vent. The funnel shape is said to improve airflow while reducing turbulence. The new 6 pole motor and redesigned bearing lower noise further. This fan, as mentioned already in the review has the slowest start up speed of any fan on the market – 250 rpm.

This looks to be an FSP design – the topology is ‘Full Bridge + LLC + SR + DC/DC'. The Full Bridge implementation relates to the number of MOSFETs used in the PWM stage. The MOSFETS are responsible for creating high frequency alternating current – the best efficiency for the main transformation.

A Half Bridge design uses two MOSFETS, a Full Bridge doubles this to four – reducing the load across them all. The LLC part of the name relates to the use of two inductors and one capacitor – this smooths out the alternating current – giving very high levels of efficiency, critical to achieve 80 Plus Platinum efficiency.

This unit is engineered to very high standards, as we would expect from a high end be quiet! release. Soldering quality is good throughout.

There are no less than 8 daughtercards incorporated into the Dark Power Pro 11 850W unit (see above).

1. CM board (Cable management).
2. DC/DC board for 3.3 and 5V.
3. 5VSB board.
4. LLC board with the C of LLC.
5. Protection board.
6. Fan control board.
7. LLC control board (with IC).
8. -12V board.

3.3V and 5V rails are generated from the 12V DC after the main transformation. This unit is also equipped with two parallel placed main transformers (one for Standby 5V circuit) – to reduce heat emission and to give higher efficiency levels.

This design has two high grade 105c rated Japanese capacitors in the primary stage – rated 420v 470uF. It is always reassuring to see Nippon Chemi Con utilised. be quiet! say they have enhanced the design of the PFC stage by using special high quality plastic capacitors to reduce noise – exceeding the quality of the capacitor in the previous generation model.On this page we present some super high resolution images of the product taken with the 24.5MP Nikon D3X camera and 24-70mm ED lens. These will take much longer to open due to the dimensions, especially on slower connections. If you use these pictures on another site or publication, please credit Kitguru.net as the owner/source.











Additional technical assistance: Peter McFarland and Jeremy Price.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We test in a single +12V configuration.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
100W	1.57	3.35	1.76	5.06	6.66	12.11	0.50	5.04	0.20	-12.04
225W	3.75	3.35	3.86	5.06	15.59	12.09	1.00	5.04	0.20	-12.04
450W	7.54	3.34	8.35	5.05	30.78	12.07	1.50	5.04	0.30	-12.04
675W	11.33	3.34	12.35	5.05	47.46	12.06	2.00	5.03	0.50	-12.05
850W	1.52	3.35	1.17	5.06	63.53	12.05	0.50	5.04	0.20	-12.05

Load regulation is superb with all rails exhibiting very minor fluctuation under load.

be quiet! Dark Power Pro 11 850W	Maximum Load
	945W

We managed to get the power supply to deliver 945W before it would shut down, delivering around 85W more than rated specifications.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
760W	1.0	3.35	1.0	5.06	60.0	12.05	0.2	-12.05	0.50	5.02
165W	15.0	3.33	18.0	5.05	2.0	12.11	0.2	-12.05	0.50	5.01

The power supply exhibited no problems when dealing with our intensive Cross Loading test. It was tasked with 60A on the +12V rail and it held at 12.05V. The other rails delivered good results also.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.

ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output	Ripple (mV p-p)
+3.3V	50
+5V	50
+12V1	120
+12V2	120
-12V	120
+5VSB	50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
100W	10	10	10	10
225W	10	15	15	10
450W	10	15	15	10
675W	10	15	15	15
850W	10	20	20	15

Noise suppression results are excellent, peaking at 10-20mV on both +3.3V and +5V rails. The +12V rail peaked at 20mV under full load – well within the rated parameters.

Efficiency (%)
100W	89.42
225W	91.78
450W	94.21
675W	93.61
850W	91.56

Efficiency is extremely impressive, peaking at 94.21 percent at 50 percent load. This drops to around 91.5 percent at full load.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the power supply we have taken it into our acoustics room environment and have set our Digital Sound Level Noise Decibel Meter Style 2 one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refrigerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
100W	<28.0
225W	<28.0
450W	29.1
675W	31.6
850W	33.1

The fan spins slowly at general load demand, with noise levels rating below 30dBa. Under higher loads, the fan spins up, but it never becomes intrusive. This is a testament to not only the quality of the fan, but the high Platinum efficiency of the unit.

At full load, the power supply is audible, but the fan noise is minor – likely to be drown out by even a single case fan.

Temperature (c)
	Intake	Exhaust
100W	37	38
225W	38	40
450W	42	46
675W	45	50
850W	47	54

The large fan helps to ensure that rising load demands are met with increased air flow.

Maximum load	Efficiency
945 watts	91.14

At 945 watts, the efficiency level measures 91.14%. Not a practical situation to be running 24/7, but worth noting.
The be quiet! Dark Power Pro 11 850W is a fantastic power supply, built to the highest standards. The class leading SilentWings 3 fan emits very little noise, and due to the Platinum efficiency of the power supply it never has to work that hard – even when delivering 850 watts.

This means the be quiet! Dark Power Pro 11 850W is ideal not only for a high specification gaming rig, but for the audience who want a close to silent system for a living room, or bedroom environment.

FSP are not a company I would immediately associate with a high end unit, but the Dark Power Pro 11 is a design clearly not accepting any compromises. They are using high grade components throughout, supplemented by 105c rated Nippon Chemi Con capacitors in the primary stage –  a Japanese brand we rate highly.

There are a total of 39 aluminum solid capacitors in the unit and we couldn't force the supply to generate any noise related to coil whine. This is a Full Bridge + LLC + SR + DC/DC design and it didn't exhibit any weaknesses during several days of stress testing. It actually managed to deliver close to 950watts (+100 watts) before shutting down safely.

The inclusion of an ‘Overclocking Key' is an interesting decision. The end user can decide whether to run the supply in single rail, or the factory default four rail mode. We would run the supply in single rail all the time, as we expect many users will also.

The modular design will be welcomed by appearance driven system builders, and while this Dark Power Pro 11 is not a ‘pure modular design' there is only one hard wired cable running from the chassis – the primary ATX connector … which is always needed.

Technically, the Dark Power Pro 11 850W delivers the goods. Ripple suppression passed all the tests, and load regulation could be classed as very close to class leading. Efficiency rated at just over 94 percent at close to 50 percent load, which is magnificent.

Right now we have no links to buy, but we have been told that the price will be around the £160 inc vat mark. This is pretty much as we would expect, considering the Corsair AX860i Platinum power supply is available for £174.95 inc vat.

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Pros:

• close to silent.
• built to very high standards, inside and out.
• achieved 94% efficiency – 80 Plus Platinum.
• high grade 105c Japanese capacitors inside.
• excellent load regulation.
• ripple suppression is strong.
• delivered close to 950Watts before shutting down.
• competitively priced.
• no coil whine.

Cons:

• Stiff competition between £150 and £200.

Kitguru Says: The be quiet! Dark Power Pro 11 850W is a fantastic power supply well suited for a new high end system build.

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