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 DEEPCOOL Captain EX 240 RGB Cooler Testing Results, Maximum Fan Speed
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  • Yuriman - Thursday, December 14, 2017 - link

    It would be nice to see some common heatsinks within the same price bracket included in the comparison charts, even if it's only a handful. They're direct competition after all.
  • HollyDOL - Thursday, December 14, 2017 - link

    I have to agree, otherwise the results are quite relative.
    Put in at least a couple for reference (like Intel highend stock, AMD highend stock, and some elite one like Noctua NH-D15), it would make the info much more worthwhile for general public
  • HollyDOL - Thursday, December 14, 2017 - link

    not like stock coolers could hope to do anything except bbq with 340W load ofc...
  • Dr. Swag - Thursday, December 14, 2017 - link

    Awesome! A decent alternative to the S24 when it comes to quiet AIOs that also has rgb!
  • sweetca - Thursday, December 14, 2017 - link

    Catchy name.
  • Lord of the Bored - Saturday, December 16, 2017 - link

    "I am Captain DeepCool, of the Federation starship EX RGB."
  • ReeZun - Thursday, December 14, 2017 - link

    Sometimes I wonder... if some of these reviews are sponsored (either by one manufacturer or a group of manufacturers, to boost brand exposure and potentially sales)... and not necessarily direct monetary sponsorship. I also wonder... if the reason Anandtech didn't include a high-end air cooler (e.g., NH-D15)... is because it would make a strong case for the AIO solutions making a very poor value proposition... especially when considering noise/cooling ratios... and, in turn, rendering this entire review pointless.
  • E.Fyll - Thursday, December 14, 2017 - link

    Actually, the answer to your question is far less complicated than that. We only compare air coolers to air coolers and liquid coolers to liquid coolers because each represents a specific type of product. It's an "apples to apples" kind of thing. I also personally do not believe that these two actually compete with each other. Users are much more likely to go for an AIO cooler because they want easier access to their system, or because they just don't like a 2kg piece of metal hanging off their motherboard, or just because it "looks cool", than for the performance. If acceptable performance is all that a user needs, an average air cooler can do the job just fine, they do not even need a NH-D15 to begin with.

    Besides that, the magic of having and using professional equipment like ours is that everything is both repetitive and comparable. They were all tested on the exact same device and everything is in our methodology page that can be found in every cooler review. Long story short, you can easily go to our review of the NH-D15 cooler (or any cooler that you'd like to compare, regardless of its type and platform) and just compare any of its performance figures to any AIO cooler that you want to, taking into account your personal requirements too.
  • tricomp - Thursday, December 14, 2017 - link

    Sorry no.. it is green apples to red apples in most buyers considerations.. or dreams, and they really need to know what they are paying extra in case their dream comes true.
  • rtfmx9 - Thursday, December 14, 2017 - link

    I think that "apples to apples" does not hold here. After all, both liquid and air coolers serve the same purpose. It would be nice to be able to compare them without having to do research through Anandtech's archives. Is it possible that once comparison is made obvious liquid coolers don't make sense from the cost/performance point of view? I don't know since review does not try to inform me from that perspective. My guess is that there are many people who would like to inform themselves of whether upgrade to a liquid cooler would make sense or not but to do that you recommend that they dig though the past reviews instead of you offering that information in your review. All for the sake of keeping apples and oranges separated. I don't buy that reasoning.

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