Be Quiet! Dark Power Pro 11 1200W PSU Review

be quiet! says it's committed to building silent products, including the company's top PSU line, the Dark Power Pro 11. In this review, we will put the 1200 W Dark Power Pro 11 model to the test, which promises good performance and silent operation.

Reviews
By Aris Mpitziopoulos
published

Early Verdict

A silent 1.2 kW PSU, one of the very few in its category, that offers decent performance along with increased reliability. However with this amount of money are enough alternatives offering higher performance, with increased noise output however in the majority of cases.

Pros

  • +

    Full power at 49 °C • Ripple Suppression • Quiet operation • Quality (FDB) fan • Number of connectors • Japanese caps • OCK Feature • External Fan control • Warranty

Cons

  • -

    Price • Hold-up time • Efficiency and load regulation are a little behind the high-end competition • No stealth or flat cables

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be quiet! Dark Power P11-1200 Power Supply Review

be quiet! is one of the most significant German PSU manufacturers to focus on making products that operate silently, as the company's name implies. Besides PSUs, be quiet! has a rich portfolio of cooling solutions, and a while ago, the company also released a high-end case. Currently, be quiet! has enough PSU lines to cover all market segments and user needs. Its flagship series is the Dark Power Pro 11, which took the lead from the Dark Power Pro 10 line, which is still available on the company's site. Whereas some of the previous Dark Power Pro PSUs were built by Seasonic, the new line is manufactured exclusively by be quiet!'s favorite original equipment manufacturer (OEM), FSP. As it seems, Seasonic either wasn't flexible in fulfilling be quiet!'s demands or its prices were significantly higher (or a combination of both). It's important to point out that the design of the new Dark Power Pro 11 units was done by be quiet! FSP just handles the manufacturing process, as be quiet! doesn't own a manufacturing line. This means that be quiet! engineers have the required knowledge and experience to design the PSUs they offer, which will allow them to distinguish these PSUs from most of the competition.

The reality is that, in most cases, companies that include PSUs in their portfolios simply change the labels on the PSUs that the OEMs deliver to them or just ask for some slight modifications before rebranding the products as their own. Manufacturers like Seasonic, FSP, Enhance, Super Flower and others sell their products to other companies. In many cases, the main differences are only cosmetic, such as the external design of the PSU, while internally, the platforms remain the same regardless of the company that rebrands and sells the final products. However, there are some companies that have PSU engineers on staff putting them in a position where they can ask for modifications to the manufacturer's platforms. However, it is still up to the manufacturers to implement these changes, and much of this depends on the relationship between the company and the OEM.

Currently, the new Dark Power Pro 11 line consists of three models of different capacities: 850W, 1000W and 1200W. We have already evaluated the smallest-capacity PSU in this line, the Dark Power P11-850, and now it's time to take a closer look at the most powerful of the three units, which operates very quietly even under tough conditions, according to be quiet!. Through our tests, we will see whether these claims stand; based on our previous experience with this platform, we are confident that it won't let us down.

Two interesting features of the Dark Power Pro 11 line (which were also present in the previous line) are the overclocking key and the four fan connectors through which the PSU can power directly, and thermally control, an equal number of fans. The first is a simple switch (or a jumper) that converts the PSU from a multi-+12V rail to a single +12V rail unit. This feature can eliminate any problems that may arise once you begin overclocking power-hungry graphics cards, including the triggering of the overcurrent protection (OCP).

Specifications
be quiet! Dark Power Pro 11 1200

The Dark Power Pro 11 1200W, like the other two units in this line, features 80 Plus Platinum efficiency, can deliver its full power continuously at up to 45 degrees Celsius (113 degrees Fahrenheit) ambient temperature and is Haswell ready. In addition, it is equipped with all available protection features, including overtemperature protection (OTP) and OCP, since it has four +12V rails. According to be quiet!, the 135-mm (5.3 inches) Silent Wings 3 fan was developed exclusively for use in PSUs. In comparison, competitors mostly use general-purpose fans, many of which are not suitable for this kind of use. The Silent Wings fan is equipped with a fluid dynamic bearing (FDB), which is considered the best solution for increased reliability and low noise output. As you can see from the table above, there is no semipassive mode, but this isn't necessarily a downside if the unit's fan rotates at low speeds at light loads. On the contrary, we believe that a semipassive mode with a long duration can apply huge stress to heat-sensitive components like electrolytic capacitors. Finally, this product's price is quite high, and the warranty period is adequate; however, many competitors in this price category offer even longer warranty periods.

Power Specifications

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Rail3.3V5V12V112V212V312V45VSB-12V
Max. PowerAmps25253535454530.5
Watts1501188156
Total Max. Power (W)1200 (Peak 1300 / 20ms)

From the factory, the PSU comes with four +12V rails that can be combined into one through the overclocking switch or the jumper. The minor rails are very strong, with 150W max combined capacity, while the 5VSB rail has a 3-Ampere max current output. We believe that, in a PSU with a 1.2-kW capacity, a stronger 5VSB rail with at least 4 A should be used.

Cables And Connectors

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DescriptionCable CountConnector Count (Total)
Native Cables
ATX connector 20+4 pin (600mm)11
Modular Cables
8 pin EPS12V (700mm)11
4+4 pin EPS12V/ATX12V (700mm)11
6+2 pin PCIe (600mm)48
6 pin PCIe (600mm)11
SATA (600mm+150mm+150mm+150mm)28
SATA (600mm+150mm) / 4 pin Molex (+150mm+150mm) / FDD (+150mm)12 / 2 / 1
4 pin Molex (600mm+150mm+150mm)13
4 pin Molex (600mm+150mm) / FDD (+150mm)12 / 1
4 pin Molex - MB connector (600mm)11
4 pin Molex for Fan (600mm) / External Fan Connector (+150mm)44 / 4
Overclocking Key (600mm)11

This is a high-capacity PSU, so it is normal to see a lot of cables and connectors. Nonetheless, be quiet! clearly went above offering an extra six-pin PCIe connector and an additional four-pin Molex connector, which can be utilized by high-end mainboards that need extra juice, besides the EPS connectors. Also included are four external fan connectors with the same number of cables and a cable that connects the PSU to the overclocking key bracket, which, with the flip of a switch, combines all +12V rails into one. Users will have nine PCIe connectors, along with two EPS connectors, all available at the same time; we strongly believe that even a 1.2-kW unit will easily deliver its full power through so many connectors. Finally, all PCIe and EPS connectors use thicker AWG 16 gauges, and the same applies to the +12V wires of the 24-pin ATC connector. The rest of the wires are AWG 18, which is the standard wire size, according to the ATX spec.

Power Distribution

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Power Distribution
12V1ATX, Peripheral, SATA
12V2EPS1, EPS2
12V3PCIe1, PCIe2
12V4PCIe3, PCIe4

Power distribution is optimal, as the EPS and PCIe connectors are separated. In the photo below, you will find the modular board's rear panel, which shows the EPS and PCIe numbers that we list in the table above.

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Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

13 Comments Comment from the forums
  • Blueberries
    -12V Rail is very cool. These are really well built PSUs. I'd rather have a SeaSonic SS-1200 at this price range. I was expecting a better transient response change on the 5V rail, oh well.
    Reply
  • chalabam
    Interesting, but way too much focus on PSUs over the kW, when the system builder marathons had peak overclocked power at 750w (and mostly 500w) for years now.

    And those computers spend most of the time running at 50/100 w, where even this unit efficiency is poor.

    Good review, anyway, but I think that Tomshardware should focus on units that readers are more probable to buy. That info is more useful.
    Reply
  • chalabam
    16727117 said:
    -12V Rail is very cool. These are really well built PSUs. I'd rather have a SeaSonic SS-1200 at this price range. I was expecting a better transient response change on the 5V rail, oh well.

    Why you need 1200 W? What are you running?
    Reply
  • Blueberries
    16727128 said:
    16727117 said:
    -12V Rail is very cool. These are really well built PSUs. I'd rather have a SeaSonic SS-1200 at this price range. I was expecting a better transient response change on the 5V rail, oh well.

    Why you need 1200 W? What are you running?

    Just because it's rated for 1200W doesn't mean you're drawing 1200W from the wall. The PSU in the article is a 1200W PSU so it makes sense to compare the two.

    16727124 said:
    Interesting, but way too much focus on PSUs over the kW, when the system builder marathons had peak overclocked power at 750w (and mostly 500w) for years now.

    And those computers spend most of the time running at 50/100 w, where even this unit efficiency is poor.

    Good review, anyway, but I think that Tomshardware should focus on units that readers are more probable to buy. That info is more useful.

    Power supplies are more efficient and put off less heat when they're not near their maximum load. If your system draws 500W you don't want to use a 550W PSU, you would be straining the PSU. SLI/CrossFire builds with multiple graphic processors can achieve a power draw of over 750W on the PCI Express rails alone!

    I don't have a use for 1200W, but that wouldn't stop me from paying extra for better components, efficiency, and reduced noise.
    Reply
  • Aris_Mp
    indeed a PSU's peak efficiency is with typical loads (40-50% of its max rated capacity). However you should also take into account how long your system operates at full load. For example if your system is mostly working at idle or at low utilization then you will probably have more gain with a lower capacity PSU rather than with a high capacity one. On the other hand at high loads the stronger PSU will be closer to its sweet spot, having higher efficiency.
    Reply
  • Blueberries
    indeed a PSU's peak efficiency is with typical loads (40-50% of its max rated capacity). However you should also take into account how long your system operates at full load. For example if your system is mostly working at idle or at low utilization then you will probably have more gain with a lower capacity PSU rather than with a high capacity one. On the other hand at high loads the stronger PSU will be closer to its sweet spot, having higher efficiency.

    It is absolutely true that power supplies are usually at their best efficiency around 50% of their maximum load, but that doesn't necessarily mean a smaller PSU is better. An AX1500 can peak at ~94% 12V efficiency, which is really good, but even at 300W it's still producing 91% efficiency, and over 90% at 150W.
    Reply
  • Aris_Mp
    The AX1500i is a very special case :)
    Reply
  • Blueberries
    16732572 said:
    The AX1500i is a very special case :)

    Be that as it may it's important to look at all of the factors. Amperage, Ripple, Efficiency, Hold-up, etc. Most important of all of course is build integrity and architecture. The best PSUs do have high loads, because well, they can handle it. They'll also last longer at any load.

    An average load for an i7 user with a single high-powered video card is ~350W (gaming), a 980ti under maximum stress can be a 300-350W draw alone, bringing that up to a potential ~550W. In this scenario an RM750X is gold rated and will perform better than a Supernova P2 650W which is platinum rated. Both are extraordinary power supplies and I'd use either one. My point is, maximum load shouldn't matter. If a power supply meets more than your demands consider that a good thing. Most people aren't going to buy these PSUs unless they have a use for them because there's other options available.

    The Dark Power Pro 11 in this article retains >90% efficiency from 200W-800W, which is a wide range, and your system load would want to fall between that range to be in the "sweet spot." A smaller PSU has a much smaller "sweet spot," but it could prove to be better.
    Reply
  • mctylr
    indeed a PSU's peak efficiency is with typical loads (40-50% of its max rated capacity). However you should also take into account how long your system operates at full load.

    It is absolutely true that power supplies are usually at their best efficiency around 50% of their maximum load, but that doesn't necessarily mean a smaller PSU is better.

    All switching power supplies decrease their efficiencies as their load decreases, typically starting at or near 50% load and often rapidly decreasing efficiencies as their load falls below 20%.

    For desktop systems, unless you run a distributed computation project in the background, 80-95% of the time the system is powered on, the system is idle or near-idle. In my limited testing a desktop system likely draws 50-100W at idle, so with a 1000W power supply it's operating at 5-10% load, and thus at its worst efficiencies.

    With Haswell and newer consumer Intel's CPUs maxing out at 145W (I believe) at stock frequencies, and most video cards needing under 200-250 W maximum (980Ti 250W), a system with a single GPU rarely needs more then 600W.

    Specifying the PS for 50% load (for maximum efficiency) to match the maximum load the system is actually capable of drawing is a poor efficiency trade-off, as the system will spend the majority of time time at under 20% utilization, at its worst efficiency, that the few percentage points of increased efficiency (at 50% load versus moderately higher loads) will result in a net lost.

    Edited: Clarify first paragraph
    Reply
  • Blueberries
    16734708 said:
    indeed a PSU's peak efficiency is with typical loads (40-50% of its max rated capacity). However you should also take into account how long your system operates at full load.

    It is absolutely true that power supplies are usually at their best efficiency around 50% of their maximum load, but that doesn't necessarily mean a smaller PSU is better.

    All switching power supplies decrease their efficiencies as their load decreases, typically starting at or near 50% load and often rapidly decreasing efficiencies as their load falls below 20%.

    For desktop systems, unless you run a distributed computation project in the background, 80-95% of the time the system is powered on, the system is idle or near-idle. In my limited testing a desktop system likely draws 50-100W at idle, so with a 1000W power supply it's operating at 5-10% load, and thus at its worst efficiencies.

    With Haswell and newer consumer Intel's CPUs maxing out at 145W (I believe) at stock frequencies, and most video cards needing under 200-250 W maximum (980Ti 250W), a system with a single GPU rarely needs more then 600W.

    Specifying the PS for 50% load (for maximum efficiency) to match the maximum load the system is actually capable of drawing is a poor efficiency trade-off, as the system will spend the majority of time time at under 20% utilization, at its worst efficiency, that the few percentage points of increased efficiency (at 50% load versus moderately higher loads) will result in a net lost.

    Edited: Clarify first paragraph

    Yes but titanium efficiency PSUs retain 90% efficiency at a 10% load and platinum achieve at least 90% efficiency at 20% load. See: https://en.wikipedia.org/wiki/80_Plus

    If the components are good they'll be able to handle a large load. There's no such thing as a good PSU that can't handle a large load. Most platinum PSUs can handle well over what they're rated for.
    Reply