be quiet! Dark Power Pro 11 550W Review

1. Introduction2. be quiet! Dark Power Pro 11 550W (Bundle & Cables)3. be quiet! Dark Power Pro 11 550W (External)4. be quiet! Dark Power Pro 11 550W (Internal)5. High Res Gallery6. Testing Methodology7. Closing Thoughts8. View All Pages

be quiet! are a name KitGuru consider synonymous with quality. Today we look at their latest Dark Power Pro 11 550W unit – a new lower capacity model set to supplement the 850W, 1000W and 1200W units released in May this year. The 850W model earned our highest award back in May so we have high hopes for this 550W unit.

This week be quiet! are launching 550W, 650W and 750W models. All of these supplies are modular designs and feature 80 Plus Platinum efficiency (up to 94 percent). be quiet! have been able to achieve such high efficiency levels due to the new Half Bridge + LLC + SR + DC/DC topology – I discuss this in more detail later in the review. Capacitors have also seen an improvement over the previous generation.

Those of you particularly adverse to noise will be pleased to hear that the units incorporate high grade 135mm SilentWings 3 fans with low rotational speeds.

Dark Power Pro 11 (550W-750W) Overview:

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

Pricing:

• be quiet! DARK POWER PRO 11 550W. £115 / €154 / $149
• be quiet! DARK POWER PRO 11 650W. £130 / €175 / $164
• be quiet! DARK POWER PRO 11 750W. £150 / €199 / $179

Anyone who has seen a be quiet! product in the last 2-3 years will immediately recognise the box artwork. It hasn't changed overnight. A high resolution image of the product is clearly evident on the front of the box. Capacity is listed under the image, which in this instance is 550 watts.

The rear of the box highlights details on the cabling configuration of the power supply. We will address this later in the review.

The primary box is split into two sections. The left side holds the cables and accessories. The right side has the power supply encased between two thick pieces of grey foam – with the user manual resting on top.

be quiet! include a nice accessory package including plastic and felt cable ties, screws and external fan headers. The overclocking key (above left) allows the end user to switch between single and multi rail 12V modes. There is also an overclocking jumper in the bundle.


be quiet! have equipped the 550W power supply well, including two PCI e cables with two 6+2 headers on each. Another cable is included with a single 6 pin header – for those users running with a lower end solution who want to keep cable routing as neat as possible.


The be quiet! Dark Power Pro 11 550W power supply is finished to a very high standard, in black – suitable for any colour of system build. The paint work is very resistant to scratching and the unit passed our ‘screwdriver' test without a problem.

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. This fan is based around a 6 pole motor with redesigned bearings. Noise levels are minimal and it has the lowest start up speed of any fan on the market – less than 220 rotations per minute.

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

This is not a ‘pure' modular supply – a single ATX cable emerges from the right side of the case. This cable is always used in a system build so this isn't an issue. Along the left side of the modular panel are a series of fan headers, which can be used for fan connection. An OCK header is also available which lets the user 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. There are now two completely separate P8 connectors on the panel which helps improve load distribution – especially for those users rocking a dual CPU motherboard.

be quiet! are using two rubber style brackets on either side of the power supply, to help reduce chassis vibration. You can see them removed in the images above. We don't recommend you do this as one of them is ‘stuck' to the chassis and will never rebond.

be quiet! Dark Power Pro 11 550W
DC Output	+5V	+3.3V	+12V1	+12V2	+12V3	+12V4	-12V	+5Vsb
Max Output	22A	25A	20A	20A	25A	25A	0.5A	3A
Max Combined Wattage	110W		45A/540W _______________ Total 550W				6W	15W

The be quiet! Dark Power Pro 11 550W is a capable unit, and considering the modest overall capacity the +12V rails are strong, delivering a total of 45A.


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 – 220 rpm.

This fan is rated slightly differently to the one we saw in the 850W unit earlier this year. The 550W fan is labeled ‘BQ SIW3-13525-MF' and the fan inside the 850w unit is labeled ‘BQ SIW3-13525-HF'. The MF model in the 550W unit has a maximum rated rotational speed of 1,200 rpm and operates at 0.4A – the HF model used in the higher capacity units has a maximum rated rotational speed of 1,500 rpm and operates at 0.56A.

The topology of this particular unit is ‘Half Bridge + LLC + SR + DC/DC'. The topology of the higher capacity units is ‘Full Bridge + LLC + SR + DC/DC'. So what exactly does this mean?

A 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, this is important for higher wattage units. 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.

The Dark Power Pro 11 can use frequency modulation (FM) along with pulse width modulation (PWM) to adjust the power transformation. At around 10-15 percent load, the LLC circuit will modify the frequency to give excellent efficiency levels. Good results can be reached with low frequencies at high loads, and vice versa.

The Dark Power Pro 11 utilises zero voltage switching and zero current switching technology. This essentially captures power lost by other topologies with switching done at the zero line. A traditional topology cannot control the switching point to the same degree so there is some switching loss. With a ZVS/ZCS implementation this ‘lost' power is captured, giving better efficiency.

When the alternating current passes the main transformer it gets rectified and switched into 12V DC current. This process is achieved by four MOSFETS (in the lower wattage Dark Power Pro 11 units) and by eight MOSFETS (in the higher wattage units) – subsequently synchronised by using a dedicated IC. This IC (in the Dark Power Pro 11 anyway) is called the CM6901.

Like many high grade, efficient units we have tested in recent months, the Dark Power Pro 11 utilises DC/DC technology. Instead of generating 3.3V, 5V and 12V from the AC on the primary side, the lower 3.3V and 5V voltages are generated from 12V DC after the primary transformation takes place.

The engineering standards are very high, and soldering quality is very good throughout.

1. CM board (Cable Management)
2. DC/DC board for 3.3 and 5V
3. Protection board
4. LLC control board (with IC)
5. LLC board with the „L“ of LLC
6. Control circuit for PFC MOSFET´s (by IC)

The 550W, 650W and 750W Dark Power Pro 11 power supplies are complimented with 6 daughter cards, highlighted above. be quiet! claim that by using these daughter boards the interior layout is improved, helping enhance air flow. This higher build density means shorter circuit paths.

The Dark Power Pro 11 550W power supply incorporates two 105c rated Japanese capacitors in the primary stage – rated 450V 220uF. This time Rubycon capacitors are used, while we noted Nippon Chemi Con inside the 850W unit earlier this year. We consider both companies to produce some of the best capacitors for this specific market. be quiet! 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 Canon 1DX camera and Canon F2.8 24-70mm 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. You can right click and ‘save as’ to your computer to view later.

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
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We combine all +12V output for the results below.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB
	A	V	A	V	A	V	A	V
110W	1.18	3.35	1.18	5.05	8.02	12.11	0.50	5.04
220W	2.07	3.35	2.07	5.05	16.13	12.09	0.50	5.04
340W	3.04	3.34	3.05	5.05	25.12	12.08	1.00	5.03
445W	4.12	3.34	4.06	5.04	33.23	12.07	1.50	5.04
550W	5.13	3.34	5.03	5.03	41.03	12.06	2.50	5.05

be quiet! Dark Power Pro 11 550W	Maximum Load
	633W

Load regulation is acceptable across the output range. The power supply delivered 633 watts of power before it would shut down, safely.

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
493W	1.0	3.35	1.0	5.05	40.5	12.06	0.2	-12.08	0.50	5.04
153W	15.0	3.34	15.0	5.03	2.0	12.12	0.2	-12.09	0.50	5.04

The unit passed the Cross Load test without any problems.

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
110W	5	10	10	10
220W	10	15	15	10
340W	10	15	15	10
445W	10	15	20	15
550W	10	15	20	15

Noise suppression is excellent, peaking at 20 mV at full load on the +12V output. All other rails held to 10mV-15mV when fully loaded.

Efficiency (%)
110W	89.53
220W	93.12
340W	94.17
445W	93.71
550W	91.78

Efficiency is excellent, peaking at around 94% at 50% load. At full load, this drops to just under 92%. Superb results.

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 SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa) one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself. That said, measuring lower than 28dBa proves very difficult, unless in strict laboratory conditions.

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)
110W	<28.0
220W	<28.0
340W	28.7
445W	31.4
550W	33.0

We registered very little fan noise at all until around 400 watts when it started to spin up more actively. At full load, the power supply registered only 33dBa which is excellent.

Temperature (c)
	Intake	Exhaust
110W	36	41
220W	37	42
340W	41	46
445W	45	51
550W	47	56

The large, quiet fan produces enough air flow to help maintain controlled ambient temperatures.

Maximum load	Efficiency
633W	90.66

Pushing the power supply above its rated limits generates an efficiency level of around 90.66%. This is not a viable ‘real world’ situation, but its interesting nonetheless.
The Dark Power Pro 11 is the jewel in the be quiet! crown, and rightly so – our testing over the years has highlighted class leading performance from this range of power supplies, combined with stellar build quality and attention to detail.

Earlier this year be quiet! released their 850 watt, 1000 watt and 1200 watt Dark Power Pro 11 units and they scored exceptionally well in our labs. The 550 watt, 650 watt and 750 watt units have just been released and we can see that the German company have not compromised in regards to power delivery quality and high standards of finish.

The be quiet! Dark Power Pro 11 550W is professionally put together and internally the design is well thought out and uses the best Japanese components throughout, including 105c rated Rubycon capacitors, a brand which have held up well in our tests over the years.

The Dark Power Pro 11 did not exhibit any coil whine during intensive game sessions and when we analysed the supply under a ‘real world' test environment it coped exceptionally well with two GTX970's in SLi.

The inclusion of the ‘Overclocking Key' will be welcomed by many. This allows the end user to run the unit in single rail, or the factory default four rail mode. Personally, I would toggle the supply to run in single rail mode all the time and we expect many readers will do the same.

The modular design will certainly appeal to appearance driven system builders. The quality of the cabling is excellent, and there is only a single hard wired cable to deal with – the primary ATX connector. This is always needed, so the hardwired state is not an issue.

Technically there is nothing we can fault. Load regulation is first class, ripple suppression is stellar and the cross load test was handled without a hiccup. The single 135mm SilentWings 3 fan is one of the best you can get – this unit is silent most of the time, and even when delivering a full 550 watts it will be barely audible with fan emissions likely masked by one or two case fans.

Right now there are no links for a direct purchase, but we have been told by the company that UK pricing for the 550 watt model is set at £115 inc vat – this is the cheapest of all the range. The 650 watt model is priced at £130, and the 750 Watt model at £150. Currently, the Dark Power Pro 11 850 watt model is available at £164.99, the 1000 watt model £189.95 and the 1200w model £214.99. The full range of be quiet! power supplies is available from Overclockers UK HERE.

Dark Power Pro 11 are expensive power supplies – the flagship products in the be quiet! range – however you are buying a quality unit with extremely low noise characteristics, exceptionally high build quality and an excellent modular implementation with the ability to switch between single and multi rail configurations. The adoption of 105c rated Japanese Rubycon and Nippon Chemi Con capacitors in both primary and secondary stages translate to a long, reliable product life. It is worth paying a little extra for this added peace of mind.

You can also buy from ARIA directly HERE. Full range available HERE.

Discuss on our Facebook page, over HERE.

Pros:

• switchable multi/single rail.
• extremely low noise emissions.
• technically stellar unit.
• fantastic build quality.
• excellent ripple suppression.

Cons:

• expensive.
• stiff competition at the price.

KitGuru says: Don't be fooled by the low power output rating, the be quiet! Dark Power Pro 11 550 watt unit can handle a surprisingly powerful dual GPU gaming rig. It is an extremely quiet power supply and worthy of a final shortlist.

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