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, Packaging & Bundle Testing Results
Comments Locked


View All Comments

  • whatthe123 - Friday, January 15, 2021 - link

    It's really more about the pump than the thickness. Other non-asetek pump solutions like the new lian li and EK perform basically the same as the liquid freezer 2. you'd need a really large die and a lot of power pulled through it before the rad became the real differentiating factor.
  • Tunnah - Friday, January 15, 2021 - link

    What would be an interesting test is to see the temperatures with the fans running minimum speeds. I prefer quiet over temps so my 3700X/NH-D14 with 2 fans run at 300RPM-600RPM to keep it around 60c, and only spin up if it goes up to 80c. Been thinking about getting a beefier cooler so I can keep it cooler at the same sort of fan speeds.
  • lorribot - Friday, January 15, 2021 - link

    Whilst maximum cooling potential is useful for those that can configure the system in a certain way (hide in a cupboard) it is not practical for most people, what would really good is temps and fan speed at a given noise level, such as 30db, 32db and 35db, then, given your personal preference/tolerance you would then buy based on performance at your prefered sound threshold and set fans to an appropriate speed. Using 7 volts an 12 volts is pretty pointless.
    I have never seen this sort of testing in any review.
  • Galcobar - Saturday, January 16, 2021 - link

    Gamers Nexus includes noise-normalized testing in its cooler and case reviews, and has covered most of the Liquid II line. Artic is at or near the top of the GN cheers for thermal/noise efficiency, despite the relatively lower MSRP. The fans of course play a large role in this, which is in line with their near-Noctua results in Optimum Tech's fan roundup.
  • bug77 - Friday, January 15, 2021 - link

    I've always built my own system, but never understood the appeal of these. They're not quieter than air cooling and they come with a bunch of problems on their own.
  • Spunjji - Monday, January 18, 2021 - link

    They can be quieter than air cooling if you're doing some serious overclocking, not to mention you then avoid having the 1Kg+ of weight you'd need hanging off your motherboard to get similar cooling potential with air alone. It can also allow you to remove the heat directly from the case with the right case design (venting from the top).

    I'd agree that it's overkill for the majority of users, though. The last time I used AIO coolers were with adaptors for GPUs, which made way more sense - I could get a combined cooling and noise level combination that was simply impossible with air cooling, but cheaper than a custom loop.
  • Solidstate89 - Monday, January 18, 2021 - link

    I don't know why you'd make such a blatantly false statement but these AIO coolers are almost always quieter than an air cooler.
  • Dug - Monday, January 18, 2021 - link

    That is not true if you look at any normalized sound testing. In almost all cases a good air cooler will be quieter because you don't have pump noise, and you have less restricted air flow. Noise is going to come from two things, fans and pump. While pump noise may not be loud, it can be annoying. Like a mosquito isn't loud, but killing it makes all the difference in the world.
  • cellarnoise - Friday, January 15, 2021 - link

    1st post on a product review since 1997 ish? I can't remember my original user name or password, but keep coming back here a long time. I'm preparing for a 5950x if I can ever find one, so I bought this 420. Love it. Running in a slightly modified Fractal s2 case that I modified to move the 420 closer to the glass side of case away from the motherboard so my mid-height RAM could fit without touching the AIO. Love it! Running on 1700x at 3.8 BOINC load 24/7 it is much quieter as fans sit under 500 rpm for 130w load. At anything but idle this runs much quieter than the single tower Noctua NH-U14s that I had on this before and I have another equivalent on an 1950x sitting in a solid sided Fractal R5. I love the silence and hope it does well on the 5950x at 250W or so.
  • Dorkaman - Saturday, January 16, 2021 - link

    Hi are the radiator copper or aluminum? Custom looos are usually copper and have considerably better heat sink.

Log in

Don't have an account? Sign up now