The be quiet! Straight Power 12 750W PSU Review: Proficient Platinum Power

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. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs – 2014 Pipeline post.

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.

In our elevated ambient temperature test, the Be quiet! Straight Power 12 750W PSU experiences a notable dip in efficiency, dropping to an average of 90.6% under a 115 VAC input and 92% with a 230 VAC input. Despite this marked decrease from its optimal performance levels, the PSU remarkably exhibits no thermal stress indicators, even when operating at its maximum capacity.

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 to 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 750 Watt version of 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 current $140 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.