Inside be quiet!

How the Straight Power 10 power supply came to be

With our latest PSU, Straight Power 10, we were certain from the outset that we could excel in every possible way. And we did exactly that — all models of the latest generation are far more advanced than their predecessors.

In this issue of INSIDE be quiet! we want to share with you the precise steps we took to achieve our ambitious goals. Instead of simply quoting boring facts in a datasheet, we want to show you how our new power supplies were created. We think it is about time that we provide technically interested end-users with in-depth details. We want to show you just how much effort is needed to satisfy the desires of customers, as well as meet our own high standards of quality. That is why we are giving you this insight into our laboratory and product management.


Starting point

Before we began developing of Straight Power 10, it was of course necessary to study current market trends and the analysis of reviewers, dealers and social media channels. It was even more important to discover what our user community wanted from a new PSU. Only when we were clear on all these points were we able to work out the details of specification and design. Only one parameter was decided on before we started our research: the price of the new PSUs should not exceed that of the previous generation.

Next we contrasted the Straight Power E9 with our plans for Straight Power 10. We had to compare what features the existing platform provided with what we wanted the new one to offer and what we could actually realize. After a number of prototypes, we managed to draft a version that combined the best specifications with the highest quality. The new model contained all the state-of-the-art features and enhancements necessary to satisfy the wishes expressed by users, and so we felt we were on the right road.

Using market feedback as challenge and motivation

By now it must be abundantly clear that we attach great importance to the feedback and suggestions we get from our end users, our testers and our dealers. The product management team is thus presented with an enormous challenge: keeping an eye on our competitors with regard to the prices and features they offer, and at the same time analyzing the feedback already mentioned, in order to precisely determine our market position and clearly define our objectives. On the one hand the new product has to satisfy prudent and feasible desires, while on the other hand it must outdo comparable models on the market and in so doing set the bar higher.

Some of the essential questions the team asked themselves included: What technical characteristics and efficiency do customers expect? Will it require cable management and if so how long must the cables be?

Their goal was to design a power supply that not only conformed to the expectations of customers but also complied with the technical requirements of regulatory authorities and component suppliers.

The key technical objectives in the development of Straight Power 10 were: better voltage stabilization and regulation, as well as a lower noise level. The latter was achieved with use of our own SilentWings 3 fan technology and by enhancing the 12-volt power supply for graphic cards. The extreme load fluctuations of GPUs can produce electrical noise in the power supply. We will look more closely at this phenomenon later in this article.

In order to achieve all these objectives, and keep the price of Straight Power 10 approximately even with its Straight Power E9 predecessor, we chose from available technologies and platforms those that met as closely as possible our own requirements and those of our customers. In close cooperation with all of our parts manufacturers, we worked and fine-tuned repeatedly until the product corresponded to our ideas and goals. Only in this way was it possible for us to finish with a truly first-class product

DC-to-DC regulation for everyone

As a first major step, the platform for the Straight Power 10 series was completely redesigned and, through many prototype tests, further enhanced. Early in the course of development we adopted full DC-to-DC converter technology for the new series, and by that we addressed the frequently voiced desires of end users.

In Straight Power 10, the transformer produces only 12V voltage, which will be rectified by voltage modules (regulators). This 12 volt output supplies not only the 12-volt rails, but also the 3.3- and 5-volt-rails via additional DC-to-DC voltage converters. Using DC-to-DC voltage conversion off a single rectified transformer output results in improved voltage regulation, higher stability and better cross-load characteristics than can be provided by older generation PSUs, including the Straight Power E9 series. With an extremely good cross-loading factor, the latest Straight Power is well-prepared for the latest HASWELL generation CPUs from INTEL. The output coil for 5V is now separate compared with Straight Power E9: it is in fact an extra component. In the Straight Power E9 the coil was combined with the 12V as a single coil. This has the advantage that inductive interference can no longer occur. In addition, we now use two integrated circuits on the DC side. One is for the 12V rail (synchronous rectifier) and the other for the 5V and 3.3V voltage converters. The advantage of two ICs handling the regulation independently is that it results in higher stability.

This picture depicts an early prototype of Straight Power 10, which comes pretty close to the final product.

Image: Early Straight Power 10 prototype

Reducing noise to practical inaudibility

We modified two fundamental things to achieve this very ambitious goal. First, we replaced the film capacitors in the power factor correction (PFC) area with a more robust fixed winding to suppress high-frequency noises, with the result that all “electrical” noise effectively ceased. We tested over ten different types of parts before we decided on the one now used in Straight Power 10.

The second step in decreasing the noise of the Straight Power 10 was more difficult: developing a completely new fan and power supply housing. From the outset we were well aware that noise eduction is best achieved by eliminating potential sources of vibration. That’s why we worked with a new partner to develop a six-pole fan motor with premium fluid dynamic bearings, especially for the Straight Power 10, which not only runs effectively at less than 200 rpm but also runs smoothly at a little over three volts. Most importantly, this new fan generates almost no motor, bearing or airflow noises even when under load. Straight Power 10 is the first power supply that produces a background noise of just over 10db(A) under a low running load.

To further reduce turbulence, we optimized the arrangement of the fan grid struts, the distance between the fan grid and the fan, and the component layout on the PCB.

Die Elektronik für die Lüftersteuerung im Netzteil wurde verändert, um eine Startspannung von etwas über 3V sicherzustellen. Allein diese eine Entwicklungsaufgabe hat viel Zeit und Ressourcen gekostet, war aber notwendig, um ein völlig neues Qualitäts-Niveau zu erreichen. Vergleichen wir den Entwicklungsverlauf von Form und Funktion:

Anyone who takes a close look will see not only the new fan design, but also notice the modified intake and the amended geometry. Using a funnel-shaped inlet we were able to minimize audible turbulence significantly yet still generate consistent airflow. The newly developed six-pole motor, together with its very quiet running bearings, offers an almost inaudible propulsion unit at all speeds. As already mentioned, the Straight Power 10 fan starts and runs at just under 200 rpm using around three volts, and therefore qualifies as the first power supply to produce little more than 10db(A) when running. It renders semi-passive fan concepts, along with their associated running and failure risks, simply unnecessary.

Image: Not yet 190 rpm and the fan is running smoothly

Of course, the results we achieved sound simpler to implement than they actually were in the laboratory, and a lot of time-consuming work was necessary in the anechoic chamber so that the final result would be convincing. In fact, we even upgraded our anechoic chamber, which is not only decoupled and very well insulated, but also sound-proofed internally with a special lining of acoustically absorbent material.

A robust solution for problems with high-performance graphic cards

Time and again we hear customers report that their graphic cards emit high-frequency noises under certain load conditions. Many PSU manufacturers fail to recognize their own problems in this regard: due to energy-saving mechanisms in the present range of graphic cards, the core voltages and loads of the GPUs can vary in the space of microseconds. When operating under maximum load, this can in turn lead to significant current fluctuations on the PCI Express power lines. These fluctuations can cause the coils of the voltage converter on the graphic card or the power supply to oscillate. And this then is heard by users as high frequency noise.

Discussion of this matter becomes entangled in whether or not single or multi-rail power supplies are the solution, yet the cause of the problem actually lies elsewhere: high-frequency load fluctuations result in extreme and unsmoothed current spikes and above all make faster demands of most power supplies than they can switch. This is what leads to the sounds mentioned above, arising from the coils of the voltage converter.

be quiet! sought a suitable solution and finally found one. We have enlarged the output capacity of the smoothing electrolytic capacitors on the 12V-rail, which now has four capacitors on the main PCB, and we have also installed further solid caps (low ripple current) for PCBs with cable management in order to directly filter the peaks in demand coming from the graphic card.

Compared with Straight Power E9, we have significantly enlarged the capacity and frequency stability of these capacitors. Not only does this improve operational reliability and the ability to effortlessly overcome load fluctuations and current spikes, but the whole power supply benefits from a significantly extended lifetime.

This example illustrates how important it is to cooperate with other component manufacturers and observe the market. Even small features and modifications made to other components can have a massive effect on the power supply. That is why we are constantly developing solutions for the highest possible compatibility and lowest noise.


Evidence of this comes from our latest test runs: where other manufacturers must install power supplies with at least 850 or 1000 watt capacity to cope with the rapid fluctuating current spikes (and yet these still produce extremely high levels of unwanted noise), our Straight Power 10 with only 500 watts passed all tests and benchmarks inaudibly yet with flying colors! Testing was performed with a Z97 platform and various graphic cards. Among these were a GTX Titan-Z and an R9-295X2. With this extreme loading the system remained stable at all times and the power supply was inaudible, even though the load exceeded 100 percent.

(Please note that, while our testing serves to show how superior Straight Power 10 is, in fact a power supply of at least 650 watts should be used in systems intended to operate permanently under load.

We listen to you, because constructive feedback is extremely important to us

Customer feedback is directly responsible for the eight-pin EPS connector cable (CPU power) being longer in the new Straight Power 10. This enables users to install it in very large cases. Additionally, as requested by many customers, we now ship the modular cable connectors completely in black.

As logical consequence of the graphics card problems described above, we now use 12-pin connectors for the PCI Express power supply cables for graphic cards, and further provide a separate cable for each connector. Of course, we also calculate our cable gauges so they are always sufficient to cope with the peak performance demands of high-end graphic card.


As you can see from this look into the development of Straight Power 10, we do everything in our power to design a product that exceeds the specifications of the previous generation. We apply learning from the feedback of purchasers, dealers and reviewers. We closely study the current market situation, and we put the highest value on feedback from our customers. Our aim is to constantly satisfy your desires and establish new technologies, while always making products better than their predecessor in terms of performance, quality and low noise emissions. That is why we invest so much time and effort into the development of our products.

The result, in the form of Straight Power 10, will win you over in all respects—because the new Straight Power 10 is not only equipped with the latest technology and is quieter than ever before, but also because it was created with the highest attention to detail and exceptional commitment to quality.