Cold Test Results

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 efficiency of the Be Quiet! Straight Power 11 750W PSU is not going to break any records but it does meet the 80Plus Gold certification requirements. Across the nominal load range (20% to 100% of the unit's capacity), the average efficiency of the Straight Power 11 750W PSU is 91.9% and 90.2% with an input voltage of 230V and 115V respectively. Where the Straight Power 11 fails to impress is under very low loads, with the efficiency diving below 75% when the load is lower than about 40 Watts.

The Be Quiet! Straight Power 11 750W PSU displays exceptional thermal performance, maintaining comparatively low internal temperatures considering its efficiency rating, class, and components. By looking at the air temperature graph we can surmise that the PSU does a great job handling its thermal losses with excellent heat dissipation capabilities.

Although the Straight Power 11 750W PSU lacks any advanced form of fan speed control, the unit is virtually inaudible while the load is low. However, the speed of the 135 mm fan continually increases alongside with the load and its noise will be noticeable as soon as the load is close to or greater than 350 Watts. Beyond that point, the speed of the fan will increase even more sharply and will reach borderline uncomfortable levels when the PSU’s load is greater than 650 Watts.

The Be Quiet! Straight Power 11 750W PSU Hot Test Results (~45°C Ambient Temperature)
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  • Death666Angel - Wednesday, November 7, 2018 - link

    Thanks for the review! I generally like BeQuiet stuff. I have a Dark Rock Pro 2 that I bought used for cheap as my CPU cooler and a Straight Power E9-CM 480W PSU that I also bought cheap used. That gives me a pretty much silent PC in combination with a Core i5-4570S @ 1V @3.6GHz and a 960 GTX graphics card. This seems to have missed its mark a bit, they are usually pretty good about the noise levels. Their Dark Rock Pro coolers trade blows with Noctua ones while usually being a bit quieter.

    One thing I would like to ask about this statement: "the efficiency diving below 75% when the load is lower than about 40 Watts."
    Will you be able to maybe give us an article detailing idle power consumption of current generation (maybe even older generation) hardware, to see how relevant such a deficiency is? If I were to buy a 750W PSU, it would be for a top of the line overclocked 8 core CPU and a smiliar, top of the line overclocked GPU. A reasonable overclock on air would likely still mean the system draws less than 500W with a handful of HDDs/SSDs and no weird stuff. What would be the idle power draw of such a system. Maybe compare an overclock via offset to one via fixed voltage? Is 40W a reasonable target for idle power draw of modern, high end systems? How are the default BIOS settings regarding power saving mechanisms set?

    And to be fair to BeQuiet, at 40W, the absolute power consumption of the PSU is still rather small. The Corsair SF450 Platinum has about an 80% efficiency rate at 40W (cold test) and the BeQuiet about 70%. If my maths checks out, the power draw at the wall is 57W vs. 50W. If your PC idels 24/7/365 at German electric bill prices (about 24C/kWh for me), you'd pay 14€ more vs more efficient designs. Yes, it's a deficiency they need to work on for the next generation, other manufacturers are better about it. But I'd still pick this PSU than one bundled with a standard PC case or one from Thermaltake, Chieftec, LC-Power and other more or less no-name brands without reviews. :)
  • Gastec - Thursday, November 8, 2018 - link

    My old PC (i7-860, GTX 670, 8 GB DDR3 1600 MT/s, two SSDs, one HDD, 1 cpu fan, 2 case fans) idles at 35-40 W. According to this article their system with a GTX 1080Ti idled at 76 W. Other newer systems out there seem to idle at ~90-95W (which I find a bit too much).
    On the be quiet! Straight Power 11 750W is €125, the Corsair SF-450 Platinum costs €108, but it's a 450W PSU. The 600W SF-600 Platinum costs €120.
    The least expensive Corsair 750W Platinum PSU, the HX750 is €140.
  • Ravenmaster - Wednesday, November 14, 2018 - link

    Last month I RMA'd a bequiet! Silent Loop 280mm CPU cooler because after 2 months the pump went faulty and started rattling like mad. This week I had to RMA my bequiet! Dark Power Pro 11 (1200w) because it was making a popping sound when i switched it on, followed by sparks coming out of the back. Had put my old EVGA PSU back in and switch the CPU cooler for my old Corsair H100i. The older parts are louder but at least they're not faulty and they do the job. Never gonna buy bequiet! components again. Their case fans are second to none but their components are trash for some strange reason.
  • s.yu - Wednesday, November 21, 2018 - link

    Hence the exclamation mark? ;)

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