Pros, Cons And Final Verdict
The new Dark Power Pro 11 line is an important milestone for be quiet!, since it's the first time the company has designed its own platform. Because be quiet! Doesn't have a PSU manufacturing line, which is the case for most companies in the PSU market today, FSP is the OEM. The Dark Power Pro P11-1200 is one of the most silent, high-capacity PSUs that we have ever evaluated, and on top of that, it offers good performance along with some nice features that enthusiast users will appreciate. be quiet! used a top-notch SilentWings 3 fan to cool down this platform. Thanks to its Fluid Dynamic Bearing, this fan offers low noise and a very long lifetime. After capacitors, the cooling fan is the second weakest link in the reliability of a PSU, especially if the fan uses lower-quality bearings that aren't suitable for horizontal mounting and operation (e.g., sleeve bearings).
The new Dark Power Pro 11 line features some noticeable improvements over the Dark Power Pro 10 line. According to be quiet!, the new 1.2 kW model achieves 8.9-dBA lower noise output at full loads compared to the previous model, which is an impressive result. Currently, only three Dark Power Pro 11 units are available that cover the higher-capacity regions. In the near future, the company is planning to expand this line with lower-capacity models covering the mid-wattage category (550 W to 750 W), which would be of high interest to many users.
While the lower-capacity Dark Power P11-850, which we previously reviewed, could match the competition in its category, this doesn't seem to be the case with the higher-capacity unit. Admittedly, the competition in the 1.2-kW, high-end category is much tougher since implementations by Seasonic, Super Flower, Andyson and FSP raise the bar quite high. We shouldn't forget, though, that this is be quiet!'s first attempt to design its own PSUs, so it is expected that it wouldn't beat the more experienced PSU makers in all areas. However, the new unit is close in performance, and, with some modifications, the platform can be brought up to speed.
The most significant advantage of the 1.2-kW Dark Power Pro unit is its silent operation, which the majority of the competition can't offer. Nowadays, many users are very sensitive to the noise that their PSUs make, and as the capacity of the unit increases, it becomes even more difficult to suppress the noise output. From our noise-test results, it is clear that be quiet! lived up to its name and managed to deliver a quiet, high-capacity PSU. However, in pure performance terms, the unit is behind the high-end competition in this category. If be quiet! can afford to lower its asking price, then the price per-dollar ratio for the P11-1200 would receive a nice boost; otherwise, the company should make some modifications to increase the PSU's efficiency and tighten the unit's load regulation. In any case, if you need a silent PSU with huge capacity and some nice features (like the overclocking key and external fan control), then you should definitely take a look at the Dark Power P11-1200.
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Aris Mpitziopoulos is a Contributing Editor for Tom's Hardware, covering Power Supplies.
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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.
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.
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.
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.
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.
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.