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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  • ObamaWasRight2003 - Monday, December 4, 2023 - link

    Looks nice and great performance but cant say I want to spend 3x the price of a thermalright phantom spirit 120 on it
  • Samus - Wednesday, December 6, 2023 - link

    They are also competing directly with Noctua at this price, which is a tough sell even if it performs better, because Noctua has unrivaled support.
  • emn13 - Sunday, December 17, 2023 - link

    It's not really any better than the D15. The noise vs cooling perf in these graphs is very slightly better at high fan speeds; and very slightly worse at low fan speeds.

    If anything, I think the latter matters more (most of the time, my CPU isn't running flat out), but given the size of the margin it's all moot anyhow.

    The pricing vs. support trade off is what matter here.
  • TEAMSWITCHER - Monday, December 4, 2023 - link

    I just upgraded my Media Room PC (no Xbox or Playstation for me) and I went with the Shadow Rock 3 cooler. BeQuiet has a great Motherboard Compatibility app on their website that will help you pick the right cooler. This is very important as motherboards today have some very tall VRM cooling solutions.

    The ATX motherboard specification is crazy old now. I can't help to think that the industry could benefit from a new spec that moves the RAM above or below the CPU socket location.
  • Threska - Monday, December 4, 2023 - link

    It already is.

  • Flunk - Monday, December 4, 2023 - link

    Not having Be Quiet's last top-end aircooler the Dark Rock Pro 4 in this review is a serious omission.
  • E.Fyll - Monday, December 4, 2023 - link

    The Dark Rock Pro 5 is the latest - and I am on it.
  • XacTactX - Monday, December 4, 2023 - link

    It would be great if you could review the Thermalright PS120, it's always available for less than $40 and I have a feeling that the performance will be a few degrees worse than the best heatsinks that you have reviewed. Thank you so much for putting up this content!
  • Sunrise089 - Monday, December 4, 2023 - link

    Thank you. I know coolers aren’t the sexiest product but I appreciate the review quality and simply having the content here on the site :)
  • craznazn - Tuesday, December 5, 2023 - link

    Price to performance is a pretty big L that you guys seem to skip on. For this price, you can buy an arctic freezer II. For 1/3 the money, you can get a PA120/PA120SE. In fact, not having price/performance comparison is pretty lacking.

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