Be Quiet Straight Power 12 750W PSU Review | Tom's Hardware

The Be Quiet Straight Power 12 750W PSU excels in both build quality and performance, delivering exceptional efficiency and near-silent operation. Its fully modular design and top-tier components make it a reliable choice for mid-range to high-end systems, though careful attention to overall system balance is necessary due to its 750W capacity.

Excellent build quality

Near-silent operation

ATX 3.1 compliance

High efficiency

Tight voltage regulation

Fully modular design

Quiet under low loads

No hybrid fan mode

Limited headroom

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In the arena of PC components, Be Quiet (spelled as "be quiet" on marketing materials) is a name synonymous with excellence, known for its fusion of silent functionality and exceptional performance. The company's broad range of products, from high-end power supply units (PSUs) to sophisticated cases and cooling solutions, including both air and liquid options, is crafted with a keen eye on reducing noise while maximizing efficiency. Be Quiet has earned accolades for its dedication to achieving near-silent operation across its lineup, making it a preferred choice among those in the PC enthusiast community who seek a serene computing environment. The diversity of its offerings reflects a deep understanding of the needs of tech enthusiasts and professionals alike, with each product designed to offer a blend of low noise levels and high efficiency.

Today we're looking at the Be Quiet Straight Power 12 750W PSU, a high-tier offering in Be Quiet's PSU portfolio that exemplifies the brand's approach to product design. The Straight Power 12 series is engineered to deliver top performance and whisper-quiet operation, appealing to users who seek the optimal mix of power efficiency and sound level, without compromising on reliability and premium quality.

Currently priced at $139 in the U.S., the 750 Watt model that we are reviewing today is the weakest unit of the series, yet still enough to effortlessly power a modern gaming system with a mid-tier GPU and still well-built enough to compete with the best power supplies on the market.. We should also mention that although we received and reviewed the ATX 3.0 version of the unit, the company recently “upgraded” the unit to ATX 3.1 compliance – the unit itself remains identical, as the ATX 3.1 requirements are lower than those of the ATX 3.0 design guide, with the sole difference being the shorter sense pins on the 12V-2x6 connectors.

The Straight Power 12 750W PSU shows up in a sleek package that sticks to the classy all-black design Be Quiet has us used to, with the PSU's snapshot taking center stage on the front. Inside the box, a nylon bag and foam inserts make sure the unit gets to you without a scratch. Information about the unit and its performance are printed on the sides and back of the box.

In keeping with Be Quiet's focus on providing just what's necessary, the Straight Power 12 750W packaging contains all you need to get it up and running. Inside, you'll find a basic set of mounting screws, an AC power cable, and just a bit more to sweeten the deal - a detailed manual and some cable ties, as well as two cable straps that hold the two modular cable bundles together.

What sets the Straight Power 12 apart is the design of the modular cables themselves. It is a fully-modular design that allows for the removal of every DC power cable, even the 24-pin ATX connector, which is common nowadays. However, the all-black cables are all nylon-sleeved for a uniform look, much unlike most of the competition that is trying to be rid of nylon sleeving and use ribbon-like cables instead.

The Be Quiet Straight Power 12 750W PSU is housed in a chassis that measures 86 mm × 150 mm × 160 mm (H × W × D), making it just a tad longer than the usual ATX size. It can fit into a wide variety of contemporary PC cases without a hitch, particularly those designed with high-performance parts in mind. The size is precisely chosen to accommodate its 135 mm cooling fan, ensuring efficient thermal management.

Be Quiet has dedicated attention to the exterior aesthetics of the Straight Power 12 750W, a detail that stands out for a product designed to deliver both quality and performance. The unit boasts a satin black finish, offering a refined look, with the company's logo elegantly embossed on the right side of the chassis. The design of the fan finger guard is distinctive, featuring a unique parallel wire construction that enhances the PSU's overall appearance. On the left side, there is a sticker displaying the electrical specifications and certifications, maintaining a balance between functionality and design sophistication, with the top side kept sleek and simple.

At the back, you'll find the usual on/off switch right beside the AC input, with the unit's front dominated by modular cable connectors, each labeled with a clear white legend for straightforward identification. Significantly, the Straight Power 12 750W features an PCI 5.0 600W connector, highlighting its compliance with the latest ATX 3.0 standards. This makes it a standout choice, especially given its power output, ready to support the newest, power-hungry GPUs, yet the system’s builder needs to be considerate regarding the balance of the system’s components – even though the Straight Power 12 750W PSU can theoretically power the most power-hungry GPU currently available, it cannot handle both that and a power-hungry CPU.

The Be Quiet Straight Power 12 750W PSU incorporates a cooling fan from their own prestigious lineup, the SilentWings 3 135mm, featuring an all-black design and a fluid dynamic bearing (FDB) engine for enhanced durability and efficiency. Opting for a slightly larger fan than the norm for PSUs, this model supports the unit's design ethos of superior cooling without compromising on noise. Despite its size, the fan is capable of reaching up to 1800 RPM, a high speed for a 135 mm fan and disproportionately powerful for a 750W unit.

The Straight Power 12 750W PSU is crafted by FSP, an Original Equipment Manufacturer (OEM) renowned for its significant presence in the power supply sector, catering to both mid- and top-tier markets. FSP holds a distinguished place among the elite PSU manufacturers, owing to its long history and substantial expertise in developing PC power supplies. Their reputation for producing high-quality and reliable units is well-established within the industry, marking them as a trusted name for both consumers and professionals seeking dependable power solutions.

The Straight Power 12 750W PSU incorporates fairly advanced but proven topologies, mixing performance with reliability. The unit is equipped with a slightly enhanced filtering stage featuring four Y capacitors, two X capacitors, and two substantial filtering inductors, leading up to a pair of standard rectifying bridges that can be found on their dedicated small heatsink. Its Active Power Factor Correction (APFC) circuitry is mounted on a large heatsink situated along the edge of the PCB. This section boasts two APFC MOSFETs (R6030KNX) and a diode, complemented by a filtering inductor wrapped in a plastic sleeve and two high-quality Rubycon capacitors (330 μF each).

For its inversion primary stage, the Straight Power 12 750W PSU utilizes a full-bridge LLC topology, a proven choice for high-performance power supplies. The four bridge MOSFETs are situated on the same long heatsink that also houses the APFC components. The secondary stage sees a slight departure from the norm with four MOSFETs at the rear of the PCB handling the synchronous rectification for the main 12V line. A typical vertical daughterboard houses the DC-to-DC conversion circuits for generating the 3.3V and 5V lines.

For the secondary side's capacitors, a blend of premium Rubycon and Nippon Chemi-Con components is used, signifying a commitment to top-tier quality and reliability. The choice of capacitors makes the Straight Power 12 an all-Japanese affair, as expected from a product of its class.

For the testing of PSUs, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M 40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox and various other bits and parts.

The Be Quiet Straight Power 12 750W meets and surpasses the 80Plus Platinum certification standards, showcasing exceptional electrical conversion efficiency. With a 115 VAC input, this unit delivers an average nominal load range efficiency (covering 20% to 100% of its capacity) of 91.9%, and an impressive 93.2% efficiency when powered by a 230 VAC source. Like most manufacturers, Be Quiet received the certification rating with an input voltage of 115 VAC, where the requirements are lower – however, the 750W version of the Straight Power 12 also meets the 80Plus Platinum certification requirements with an input voltage of 230 VAC.

The Be Quiet Straight Power 12 750W PSU doesn't feature a "hybrid" fan mode, which means its fan is active from the start. Thanks to its design, the fan operates at a very low speed even when the load reaches up to 50%, ensuring that the unit runs quietly under typical conditions. As the load increases, the fan's speed increment is modest, designed to keep noise levels down. Despite this conservative approach to fan speed, the thermal control circuitry manages to keep internal temperatures surprisingly low, even at full load. This indicates high energy conversion efficiency paired with a somewhat oversized cooling system, designed to be capable of achieving top performance at minimal noise levels.

The Be Quiet Straight Power 12 750W PSU's fan operates with a controlled strategy, ramping up as needed to manage thermal output. Despite the very high ambient temperature, the speed of the fan is fairly low when the unit is lightly loaded, maintaining comfortable noise figures. This is achieved via the PSU's large heatsinks and its efficiency levels that surpass the norm for its category, leading to superior thermal management. Despite the fan's increased speed under heavy loads, the noise remains manageable with a constant load of up to 600 Watts, striking a fine balance between cooling effectiveness and noise control across most of its operating spectrum. While the fan becomes more audible with heavier loads, the internal temperatures remain remarkably low, evidencing the unit's adept balance between thermal regulation and acoustic performance.

As the fan accelerates under the thermal control system's command in the Be Quiet Straight Power 12 750W PSU, the unit adeptly regulates its internal temperatures, keeping them commendably low for its category. Still, the low internal temperatures would suggest that the designer had more headroom to lean towards low-noise operation at the expense of some thermal performance. In situations where the load exceeds 90%, the thermal control circuitry prompts the fan to reach its highest speeds, while the internal temperatures are far from the OTP trigger point. This is adeptly calculated for a top-tier performance PSU, where the designer wants to make sure that there will be no thermal stress reducing the performance of the active components while the PSU is heavily loaded, especially with a design that is likely to have to combat heavy power excursions from a gaming GPU.

The electrical performance of the Be Quiet Straight Power 12 750W PSU is very good overall. It achieves precise voltage regulation, with a deviation of only 0.9% on the 12V rail and even tighter control on the 3.3V and 5V rails. Ripple suppression is also well-managed, with maximum ripple values of 28 mV on the 12V rail, and 16 mV on the 3.3V and 5V rails, reflecting the PSU's ability to maintain clean power delivery under various loads and high ambient temperatures. While impressive, these results are consistent with what is typically seen in high-quality power supplies of this caliber.

During our routine evaluation, we examine the fundamental protection features of all power supply units we review, including Over Current Protection (OCP), Over Voltage Protection (OVP), Over Power Protection (OPP), and Short Circuit Protection (SCP). The Be Quiet Straight Power 12 750W PSU successfully passed all essential protection tests, validating its ability to safeguard itself and attached components under potential risk conditions.

It showed a liberal setting for Over Current Protection (OCP) on the 3.3V and 5V rails, with activation points at 120% and 122%, respectively. The trigger point for the OCP on the 12V rail is somewhat more generous, at 130%, which, while higher, is still within a reasonable range for an ATX 3.0 compliant PSU. Additionally, the Over Power Protection (OPP) kicks in at 126% of the unit's rated capacity, indicating a high tolerance level designed to ensure stability during power excursions and protection under various operational stresses.

The Straight Power 12 750W PSU stands out as proof of Be Quiet’s capability to deliver high-quality engineering and exceptional performance. Backed by a 10-year warranty and with a reasonable power output, it seemingly is a wise choice for anyone looking to build or upgrade to a mid- to high-range gaming PC setup. While it offers an alternative for those seeking an ATX 3.0 compliant unit without having to resort to a product with an unnecessarily high power output, PC builders need to be careful with the balance of their system’s components. The Straight Power 12 could theoretically power even the most powerful GPU currently available requiring one 600W connector but that would leave little headroom for the CPU and the rest of the system.

The design and build quality of the Straight Power 12 are nothing short of excellent. The fully modular design, coupled with all-black, nylon-sleeved cables, not only enhances the aesthetic appeal of any build but also facilitates easy cable management. The use of high-quality components from reputable manufacturers like Rubycon and Nippon Chemi-Con further underscores Be Quiet's commitment to reliability and longevity. The included SilentWings 3 135mm fan, renowned for its quiet operation and efficiency, assists the PSU's ability to maintain low noise levels without compromising thermal performance.

On the electrical performance front, the Straight Power 12 excels with tight voltage regulation and exceptional ripple suppression. The PSU's efficiency meets the 80Plus Platinum standard, a clear indicator of its superior power conversion capabilities which lead to superior thermal performance and a slight nod towards energy savings and reduced operational costs. The OCP and OPP settings are slightly more generous than what is typically expected, allowing for a bit of headroom that could be particularly useful in high-demand scenarios and when dealing with multiple power excursions. This approach to electrical protection does not compromise the unit's safety or stability, providing peace of mind to users pushing their systems to the limit.

Conclusively, the Be Quiet Straight Power 12 750W PSU represents a solid investment for any PC builder or enthusiast. Its blend of efficiency, build quality, and electrical performance, backed by a reputable brand and a 10-year warranty, offers a compelling value proposition. While its retail price point is positioned higher than expected, especially compared to other models in the Straight Power 12 series, the quality and performance it delivers are undeniable. For those in the market for a reliable, efficient, and quiet power supply, the Straight Power 12 750W is undoubtedly worth considering, particularly if found during a sale.

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Dr. E. Fylladitakis has been passionate about PCs since the 8088 era, beginning his PC gaming journey with classics like Metal Mutant and Battle Chess. Not long after, he built his first PC, a 486, and has been an enthusiast ever since. In the early 2000’s, he delved deeply into overclocking Duron and Pentium 4 processors, liquid cooling, and phase-change cooling technologies. While he has an extensive and broad engineering education, Dr. Fylladitakis specializes in electrical and energy engineering, with numerous articles published in scientific journals, some contributing to novel cooling technologies and power electronics. He has been a hardware reviewer at AnandTech for nearly a decade. Outside of his professional pursuits, he enjoys immersing himself in a good philosophy book and unwinding through PC games.

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