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 Corsair H150i Elite Capellix Liquid Cooler & iCUE Software Testing Results
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  • SirMaster - Sunday, October 25, 2020 - link

    I mean my air cooled PC fans are never faster than 800rpm. I can't even tell if it's on or off from a few feet away.
  • khanikun - Sunday, October 18, 2020 - link

    A whisper is around 30 db. NZXT Kraken X63 280mm in reviews is around 30 db at low. So I'd say that's whisper quiet.
  • willis936 - Thursday, October 15, 2020 - link

    Not even Corsair's marketing speaks so highly about these fans. Magnetic bearings are not "magnetic levitation engines" (that would be the motor, which all fans have) and they are not new.

    They're awesome and they're cool to see in case fans, but the 1st page words leave a bad taste.


  • E.Fyll - Thursday, October 15, 2020 - link

    From my point of view, the magnetic bearing is but a part of the engine that converts electrical energy to mechanical energy (airflow). You are probably referring to the engine as just the part that converts electrical energy to torque, neglecting the rest of the transmission system, which is not wrong but I would rather keep things simpler than that in my texts. I always classify fan engines based on their movement transmission system because everything else remains pretty much the same. You will find terms such as "ball-bearing engine" and "sleeve-bearing engine" frequently in my texts. The term "magnetic levitation engine" may not be entirely technically correct but definitely is better than "a 12V DC brushless motor with a magnetic levitation bearing axial transmission system" for the average person.

    Magnetic bearings may not be new by technological terms but they are just finding applications in low-cost retail market products, hence they are cutting-edge by the applicable definition of the term. There are many technologies that find their way into the retail market many decades after their initial discovery - that does not make them archaic, it only means that the conditions made their commercial exploitation applicable.
  • willis936 - Thursday, October 15, 2020 - link

    These are fair points. Thanks for taking the time to respond.
  • Pneumothorax - Thursday, October 15, 2020 - link

    I’m currently running a NH-D15 on a 9900K. Am I getting any improvement with this besides just the aesthetics?
  • Drkrieger01 - Thursday, October 15, 2020 - link

    No. You'll may actually lose cooling capacity, as Linus found out (Linus Tech Tips). He did a review showing that big heatsinks like the Noctua NH-D15 outperform pretty much all AIO water coolers when it comes to heat soak (when the heatsink/radiator hit their dissipation limits). Granted, the margin is only a few degrees, but still. What you will get with an AIO water cooler is a slower increase/decrease in temperatures as the water works as an absorbing/transfer medium. The more water in the loop, the longer it takes to bring up the temperatures.
  • Drkrieger01 - Thursday, October 15, 2020 - link

    I should also say that, if AIO coolers would actually use a copper radiator, they would outperform something like the NH-D15. None of the AIO's use copper in their radiator, and I believe this is due to a patent being held by the main AIO manufacturer.
  • imaheadcase - Thursday, October 15, 2020 - link

    I don't think that would matter though, it still follows tubing back to the CPU, that itself is terrible at temp retention. Especially when they make them long on purpose for all case types they installed in.

    But yah i found its to much of a hassle to go all out with stuff like this, really AIO coolers for me now are just about looking better and working better in case for airflow than actual performance.
  • imaheadcase - Thursday, October 15, 2020 - link

    on side note pet peeve, for whatever reason EVERY AIO cooler i have bought has never fit correctly in a case i've had..despite it showing it should before i bought it. Its mostly cosmetic things to change, like bending a small piece of metal, or something you won't notice with case cover on. But last one was a pain because after everything was installed in complete new build..it wouldn't power on. So did the normal check everything is connected, yep. I ended up finding out that radiator actually cut the USB cable connection front of case next to power button. So it was shorting out, all i had to do was unplug usb and booted up fine.

    That litte stupid problem would of been avoided if had correct specs..that was like 2 hours of trouble shooting. lol

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