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 Coolers Testing Results


View All Comments

  • Ryan Smith - Thursday, July 22, 2021 - link

    With Threadripper you should be using a full contact cooling block. While AM4-sized blocks may work, it is inadvisable. Theadripper places dies all over the place, and you do not want to risk those dies not making good contact with the cooler. Reply
  • tonyou - Thursday, July 22, 2021 - link

    The size of the CPU does affect these cooler in a big way. On the smallest sized consumer CPUs such as Intel's LGA1200 / 115X, the performance between Permafrost series and IceGem series of equivalent size will be similar. On bigger CPUs such as on Ryzen, the IceGem will consistently perform better. On Ryzen Threadripper, the performance advantage of IceGem will widen if the Permafrost was made capable of mounting on the same CPU. Reply
  • E.Fyll - Friday, July 23, 2021 - link

    Hello Citan. There you go:
  • domih - Monday, July 26, 2021 - link

    3960X here with Noctua NH-U14S TR4-SP3 with the base as large as the CPU lid. I use my computer for work, not for games. I don't care if my computer look like a dancing club with RGB all over the place. I don't care about the beige/brown. I only care about the cooling and the silence. Normal usage (e.g. development): 45C in winter, 50C in summer. Running a lot of things (e.g. VMs, databases, simulation scripts): 65C-75C in summer, less in winter. Running heavy Phoronix benchmarks: 75C-80C. No need for water cooling. Using Linux. Large PC TT View 71 Snow edition case with 6 x 140mm intake fans = Plenty of CFM to feed the air cooler. For the case, I only care about minimalist white color and a glass so it goes with the rest of the furniture and does not disfigure the room. Reply
  • vanish1 - Thursday, July 22, 2021 - link

    I feel like the people who have some sort of weird issue with RGB are just nerds with no sense of style or fashion.

    You do know you can turn it off right?
  • GeoffreyA - Thursday, July 22, 2021 - link

    It's a matter of one's taste and also a generational difference, I'd say. Many, like myself, grew up in a time when computers looked simpler. So to be bombarded with so many lights and colours today is a bit much. Reply
  • vanish1 - Friday, July 23, 2021 - link

    Lol I'll say it again.

    You do know you can turn it off right?

    and btw if you think adding lights and colors to something is a new 'trend' like holy crap man you have no concept of history
  • GeoffreyA - Friday, July 23, 2021 - link

    Didn't mean it in a bad way. I just prefer a plainer computer. A bit of light isn't bad but not too much. I actually have two fans that give off a faint bluish light. Came with the case.

    As for the motherboard, there's no way to turn off the RGB strip in the BIOS, so Mystic Light is running in the background just to do that. It's a B450 Tomahawk.
  • vanish1 - Saturday, July 24, 2021 - link

    Sounds like you made an uniformed purchase and are blaming the hardware for your error in preparation. Reply
  • GeoffreyA - Saturday, July 24, 2021 - link

    I'm happy with my hardware. No complaints with the Tomahawk except for that point. And strangely, I like the soft light of the fans. I suppose my original comment sounded arrogant. I really didn't mean it that way, and apologise.

    As in all fields of life, different people like different things. Some might prefer a brighter style. Some, a more subdued one. Also, RGB is being plastered all over hardware nowadays, so some will recoil from that. In most fields, taste changes from decade to decade. So we might see a plainer style replacing today's one. Then, when folk grow tired of that, they'll start becoming ornate again. By definition almost, fashion is temporary. Excellence is achieved when one hits on something that is unchanging.

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