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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  • Juraj_SK - Thursday, August 11, 2022 - link

    Why only 2 years warranty? Why aren't Germans be more confident with their product?
    There are competitors with 6 years warranty.
    Or is liquid cooling something that needs to replaced regularly? (the tradeoff for the piece of silence :))
  • dysnomia - Thursday, August 11, 2022 - link

    Aurora pump is very low quality, mine died exactly after one year.
  • meacupla - Thursday, August 11, 2022 - link

    If I had to guess, the warranty is shorter because the user is allowed more control over the coolant loop. If extra parts are added, that adds more complexity to the loop, and more room for user error.
    Things like: insufficient water causing the pump to run dry, adding in water that is not sterile, adding in water with too much mineral content, galvanic corrosion from mixing copper and aluminum parts, etc.

    Yes, the liquid should be replaced, or topped off, every so often. Even in CLCs, the water does eventually permeate through the tubes, and results in more air being introduced into the loop. More air means the pump has a chance of running dry, and generally more noise generated.
    Gamer's Nexus did a whole video on proper CLC configuration to minimize premature failure of the pump, and it is worth a watch.
  • Bedub1 - Thursday, August 11, 2022 - link

    It would be great to see this system retested with fans that are optimized for high static pressure. Will it still perform as well? Will it be quieter?
  • Makaveli - Thursday, August 11, 2022 - link

    Thanks for the review.

    I'm currently on a Gen 1 Corsair H150i which is very quiet. This cooler has had my eye for abit since I like that you can add on to it. So I was thinking going with

    Alphacool Eisbaer Aurora 360 CPU - Digital RGB + Alphacool Eiswolf 2 AIO - 360mm Radeon RX

    However I'm considering upgrading my 6800XT to something from RDNA 3 this christmas so will hold out to see if they make an RDNA3 compatible AIO then bite the bullet.
  • dysnomia - Thursday, August 11, 2022 - link

    They have great radiators and not bad fans. That is about all.
  • thestryker - Friday, August 12, 2022 - link

    I'm always happy to see cooler reviews pop up here because Anandtech still has my favorite methodology and is computer hardware agnostic.

    This seems like a good upgrade from the prior though I do wish they'd opted for static pressure fans. I do also find the 2 year warranty period to be on the short side since the vast majority of AIOs have increased warranty period in the last few years. I'm assuming it is due to the custom nature as most custom loop components still are at 2 year, but it's still the lowest warranty in its price/perf range by a lot.

    With PCIe 5.0 M.2 SSDs on the way maybe they'll be making a block for those which would easily slot into this and wouldn't have much impact on loop performance.
  • PeachNCream - Saturday, August 13, 2022 - link

    It really makes very little difference in day to day use after a certain point in the CPU performance curve and that point is a relatively low bar if we're being realistic with ourselves (typing this post, for example, from the keyboard of Dell Inspiron 1545 Core 2 Duo laptop running Linux and it's perfectly adequate even 12+ years after it rolled off the assembly line) so cooling solutions like this that are intended to wring a few percent in performance out of an edge case processor which land at high cost are bling toys sold to idiots intent on prodigiously throwing away electricity and generating more waste as they needlessly and mindlessly chase upgrades that external influences have imparted in them as important in seeking out some sort of meaning for themselves. The saddest part is that they're so incapable of self-awareness that they'll always have these simplistic, plant-like responses to being good little consumers of unnecessary products, capabilities, and services.
  • Makaveli - Saturday, August 13, 2022 - link

    Wow dude!
  • philehidiot - Monday, August 15, 2022 - link

    Because everyone has exactly your needs and you know what everyone should be using. Thank you for sharing your insight, oh benevolent master.

    The small market for this kind of kit is reflected in the high price compared to competitors. Some of us do genuinely have a use for this kind of thing.

    I also run a 12 year old laptop which does the day to day stuff just fine. But I also routinely hit up against the limits of my main PC. Coolers like this might just extract a few extra percent. But they also keep things quiet whilst recording audio and mine has been through several CPUs.

    If you don't see a need for it, that's just fine. Those of us who have systems running at full pelt for days on end do actually appreciate an extra few percent when that few percent is time which is also money.

    So neeeeeer, mr small willy. Bow before my humongous epeen.

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