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 only manually. Fans can have significant variations in speed from their rated values, thus their actual speed during the thermal testing is being acquired 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

The Noctua NH-U12A CPU Cooler Testing Results, Maximum Fan Speed (12 Volts)
Comments Locked


View All Comments

  • Soulkeeper - Friday, July 12, 2019 - link

    What was the RPM on the fans ?
    Did they manage to spin at their rated 2000rpm during the testing ?
  • Ryan Smith - Friday, July 12, 2019 - link


    We reached 1920 RPM, which is well within the manufacturer's margin of error for the fans.
  • sonny73n - Friday, July 12, 2019 - link

    This stupid cooler is way overpriced and outdated. Nickel does not transfer heat better than copper. Why 2 fans? They’re only mere 2 inches apart, why not slap another 2 fans on it? Why Noctua always like to make heavy and big coolers? I’ll never support self-proclaimed “engineers” who has no clues about how to make better products.
  • Korguz - Friday, July 12, 2019 - link

    ok sonny73n if you think you can design something better for less.. then go do it...
  • D@ Br@b($)! - Saturday, July 13, 2019 - link

    He doesn't have to. There are already coolers with similar performance for less money.
  • keyserr - Friday, July 12, 2019 - link

    I would like a section for performance @ normalised sound, maybe at 32db, 33db, 34db etc because 7volts gives different rpms and noise.
  • Arbie - Friday, July 12, 2019 - link

    Scythe Mugen 5 for me too. When I last found comparisons of this against eg Noctua it offered equivalent results for much less money, and has been working great for me.

    But I'll probably just go with the Wraith cooler that will come with a top Ryzen 3000 chip. That does depend on 3950X tests when they surface, but current indications are that better cooling won't increase clocks.

    This new AMD lineup will go a long way towards making high-end air - and of course any water loops - unnecessary. Those vendors must be getting nervous.
  • Qasar - Saturday, July 13, 2019 - link

    " This new AMD lineup will go a long way towards making high-end air - and of course any water loops - unnecessary. Those vendors must be getting nervous. " how so ??
  • Arbie - Thursday, July 18, 2019 - link

    Because, as I indicated, increasing the cooling on Ryzen 3000 CPUs does not appear to increase their boost clocks. I had certainly hoped otherwise. Beyond that, very few people will manually overclock Ryzen 3000 because that achieves nothing over PBO, except to waste power all the time.

    So why go to premium air? And why even consider water? Except on Intel, but any vendor dependent on sales of those chips ought to be very nervous - as I said. The niche markets involved are getting smaller (for air) and much smaller (for water).
  • D@ Br@b($)! - Saturday, July 13, 2019 - link


Log in

Don't have an account? Sign up now