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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  • osteopathic1 - Thursday, September 7, 2023 - link

    Thanks for the review. I have been looking for an AIO but dont want fancy or RGB festooned devices. This fits the bill.
  • Kevinlangford - Thursday, September 7, 2023 - link

    is $207 a good starting point for a cooler?
  • meacupla - Thursday, September 7, 2023 - link

    $207(USD) for a 280mm/360mm size AIO is on the extremely expensive side.
    280mm/360mm typically cost half that, even when sticking to recognizable brands like Deepcool and MSI.

    In fact, it is cheaper still to buy an average cost 280/360mm and then attach noctua sterrox fans onto that.
  • osteopathic1 - Friday, September 8, 2023 - link

    Thanks for the head's up.
  • deporter - Thursday, September 7, 2023 - link

    Thanks for the review, it's mostly well done. But I take issue with this statement: "just 32.1 dB(A). To regular human ears, this is entirely inaudible from a distance of one meter."
    First of all, why say from a distance of one meter, if the measurement is already at one meter?

    But most importantly, 32.1dB(A) does not mean entirely inaudible. The hearing threshold for humans is at around 0dB.

    And if you want to measure quiet gear, you need a very quiet room and some equipment which can detect very low SPL levels. That's a bit expensive, though, so I feel your pain.
  • evilspoons - Thursday, September 7, 2023 - link

    If we assume the measurement was taken completely perfectly (I know this is not reasonable) it is still likely that 32.1 dB(A) is below the noise floor of almost everyone's rooms, rendering it effectively inaudible.
  • meacupla - Thursday, September 7, 2023 - link

    Not only that, most consumer grade sound measuring devices only go down to around 30dBA.

    And then there is the pitch of the sound, which requires a very expensive professional grade device to measure.
  • deporter - Friday, September 8, 2023 - link

    >it is still likely that 32.1 dB(A) is below the noise floor of almost everyone's rooms

    No, not at all. With the windows closed, in the evenings, a room is definitely quieter than 32dB(A), unless there's a source of noise present inside. Look at various sound level charts to get an idea, or get a good SPL meter (but as I said, the good ones that measure low are expensive).
  • Ryan Smith - Friday, September 8, 2023 - link

    For what it's worth, as a suburbanite, I've never been able to do better than 30dB(A). And that was on a snowy night. Otherwise 31dB(A) is the normal floor around here. The experience has been similar for other AT editors.
  • ballsystemlord - Saturday, September 16, 2023 - link

    Living in a rural area, IE where there are few people around, I can tell you that the noise floor here is about 30db. I have measured it with a decibel meter.
    The noise that enters the house at night is a combination of the cicadas and the road noise from a 2 lane road about 1400ft away.
    And those cicadas are loud! I should measure how loud someday, but really, it can hurt your ears if you're outside of the house.

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