Testing Methodology

Although the testing of a cooler appears to be a simple task, that could not be much further from the truth. Proper thermal testing cannot be performed with a cooler mounted on a single chip, for multiple reasons. Some of these reasons include the instability of the thermal load and the inability to fully control and or monitor it, as well as the inaccuracy of the chip-integrated sensors. It is also impossible to compare results taken on different chips, let alone entirely different systems, which is a great problem when testing computer coolers, as the hardware changes every several months. Finally, testing a cooler on a typical system prevents the tester from assessing the most vital characteristic of a cooler, its absolute thermal resistance.

The absolute thermal resistance defines the absolute performance of a heatsink by indicating the temperature rise per unit of power, in our case in degrees Celsius per Watt (°C/W). In layman's terms, if the thermal resistance of a heatsink is known, the user can assess the highest possible temperature rise of a chip over ambient by simply multiplying the maximum thermal design power (TDP) rating of the chip with it. Extracting the absolute thermal resistance of a cooler however is no simple task, as the load has to be perfectly even, steady and variable, as the thermal resistance also varies depending on the magnitude of the thermal load. Therefore, even if it would be possible to assess the thermal resistance of a cooler while it is mounted on a working chip, it would not suffice, as a large change of the thermal load can yield much different results.

Appropriate thermal testing requires the creation of a proper testing station and the use of laboratory-grade equipment. Therefore, we created a thermal testing platform with a fully controllable thermal energy source that may be used to test any kind of cooler, regardless of its design and or compatibility. The thermal cartridge inside the core of our testing station can have its power adjusted between 60 W and 340 W, in 2 W increments (and it never throttles). Furthermore, monitoring and logging of the testing process via software minimizes the possibility of human errors during testing. A multifunction data acquisition module (DAQ) is responsible for the automatic or the manual control of the testing equipment, the acquisition of the ambient and the in-core temperatures via PT100 sensors, the logging of the test results and the mathematical extraction of performance figures.

Finally, as noise measurements are a bit tricky, their measurement is being performed manually. Fans can have significant variations in speed from their rated values, thus their actual speed during the thermal testing is being recorded via a laser tachometer. The fans (and pumps, when applicable) are being powered via an adjustable, fanless desktop DC power supply and noise measurements are being taken 1 meter away from the cooler, in a straight line ahead from its fan engine. At this point we should also note that the Decibel scale is logarithmic, which means that roughly every 3 dB(A) the sound pressure doubles. Therefore, the difference of sound pressure between 30 dB(A) and 60 dB(A) is not "twice as much" but nearly a thousand times greater. The table below should help you cross-reference our test results with real-life situations.

The noise floor of our recording equipment is 30.2-30.4 dB(A), which represents a medium-sized room without any active noise sources. All of our acoustic testing takes place during night hours, minimizing the possibility of external disruptions.

<35dB(A) Virtually inaudible
35-38dB(A) Very quiet (whisper-slight humming)
38-40dB(A) Quiet (relatively comfortable - humming)
40-44dB(A) Normal (humming noise, above comfortable for a large % of users)
44-47dB(A)* Loud* (strong aerodynamic noise)
47-50dB(A) Very loud (strong whining noise)
50-54dB(A) Extremely loud (painfully distracting for the vast majority of users)
>54dB(A) Intolerable for home/office use, special applications only.

*noise levels above this are not suggested for daily use

Introduction & the Cooler Testing Results
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  • hansmuff - Thursday, October 14, 2021 - link

    Hopefully not too stupid a question: how do you know when to add more liquid to the loop? Or should one completely drain and then refill in certain intervals?

    I went and looked at the manual for this loop, and it doesn't even mention the fillport at all.
    Reply
  • Stuka87 - Thursday, October 14, 2021 - link

    You cannot fill up AIO coolers. They are hermetically sealed. But quality ones lose very little liquid over time. I have run them for 5 years without issues. Reply
  • DirtyLoad - Thursday, October 14, 2021 - link

    This is not true, this cooler is an AIO and has a fill port. Also, they include a bottle of coolant. Please read review before commenting. Reply
  • damianrobertjones - Monday, October 18, 2021 - link

    Bought three AIO coolers. None of them arrived with extra coolant. Reply
  • evilspoons - Monday, October 18, 2021 - link

    The spec page for this product on the manufacturer's web site has a line that says: "Fill port: ✔"
    https://www.bequiet.com/en/watercooler/1960
    Click "technical data".
    Reply
  • ceb1974 - Thursday, October 14, 2021 - link

    I'll never go back to air coolers. Reply
  • A5 - Thursday, October 14, 2021 - link

    OTOH, I'll never go liquid. More stuff to break, costs more, and not that much better. Reply
  • meacupla - Thursday, October 14, 2021 - link

    Liquid cooling is significantly better, but only if you use a 280mm, 360mm, or larger, radiator per cpu/gpu.

    240mm is basically similar to top end air, while anything under that is not worth it.
    Reply
  • hansmuff - Friday, October 15, 2021 - link

    Quieter, it is much, much quieter. I can't hear my AIO when the machine is under heavy load for a few minutes. After that yes the fans will ramp up. But I've never been able to get an air cooler to that degree of a low ramp-up. With regular (non gaming) loads I can't hear my machine when I sit at it in the middle of the night (as in, no other noise) and I've never had that on air cooling. Reply
  • evilspoons - Monday, October 18, 2021 - link

    I have a NH-D15 with the fan ramp set up fairly carefully in my UEFI... and a Fractal Define XL R2 with acoustic padding all over the place. It takes several minutes of extended load on my 5800X before it gets louder than ambient noise. It's silent too at night just web browsing or whatever.

    I'm not opposed to the idea of a AIO but then I'd have to take a big chunk of acoustic padding off to put the radiator in the top of the case, so maybe next time. Haha.
    Reply

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