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

The NZXT CAM Software Testing Results
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  • whatthe123 - Wednesday, August 19, 2020 - link

    arctic and EK have released non-asetek coolers recently and both of them outperform practically every asetek cooler on the market, especially in price. I don't think asetek rebrands are the only choice anymore as long as you can get your hands on a freezer 2 or ek drgb.
  • edzieba - Thursday, August 20, 2020 - link

    In the US, Asetek swings their legal muscle around to quash competition. Elsewhere in the world, there are plenty of other AIO designs available.
  • jaggedcow - Wednesday, August 19, 2020 - link

    Minor point but I found it odd how they were dinged for not including threadripper mounting then in the next paragraph the reviewer says it’s not designed for threadripper‘s die size and that they wouldn’t recommend using it with a threadripper CPU. So why are we dinging NZXT for not including mounting hardware for a CPU that this cooler isn’t designed for and a configuration that the reviewer themselves doesn’t recommend? If anything, including a TR4 mount would imply that it WAS designed to also cool that chip.
  • Ryan Smith - Wednesday, August 19, 2020 - link

    "So why are we dinging NZXT"

    To be sure, NZXT is not being dinged. We're just noting that while NZXT advertises these coolers as being able to work with Threadripper, they don't do so out of the box. (And even if they did have the part in the box, we wouldn't suggest it)
  • Machinus - Wednesday, August 19, 2020 - link

    Ian, can you ebalorate on how usable the X73 is without having to use the CAM software? Can the fan and pump be controlled with typical BIOS headers?
  • satai - Wednesday, August 19, 2020 - link

    Is it better then high end air coolers?
  • inighthawki - Wednesday, August 19, 2020 - link

    The 360mm and 280mm radiator coolers tend to be give or take with high end air coolers, and generally cost more. The 240mm radiators are almost always worse, more expensive, and louder.

    The largest advantage of these is often not the improved temps, but how they mount in the case. The higher end air coolers tend to be extremely bulky and can have some difficulties fitting in smaller or more compact cases, or can have compatibility issues with ram depending on the ram height and motherboard layout.
  • Luminar - Wednesday, August 19, 2020 - link

    Repeat after me: all water cooling solutions eventually leak.
  • Lord of the Bored - Wednesday, August 19, 2020 - link

    [citation needed]
  • Spunjji - Thursday, August 20, 2020 - link

    On a long enough timescale? Sure.

    Within the lifetime of one or even two system builds? No, not in my experience.

    Can't comment for longer durations than that, as the oldest kit I've personally seen in service is about 7 years old now.

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