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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  • Spunjji - Friday, August 27, 2021 - link

    Yeah, you're definitely outside the Prism's sweet spot at that point. I'm impressed to hear that it handles 135W at all! Reply
  • AntonErtl - Friday, August 27, 2021 - link

    It handled even 190W above idle power consumption. Given that the Prism is delivered with CPUs that have 138W PPT, it definitely should be able to handle that. The 190W is surprising, though. Reply
  • Spunjji - Friday, August 27, 2021 - link

    My experience with the Wraith Prism was very good, but I think you need to stick with 65W (or below) processors in order to get the best from it. It will handle higher loads than that, you just have to accept that it won't be anywhere near quiet. Reply
  • TrevorH - Thursday, August 26, 2021 - link

    While the linked article does contain several stock coolers, are any of those available or widely used in 2021, 5 years on from that review? Are the results directly comparable with the current review? It would have been nice to include the AMD Wraith Prism in this set of results since it's not in that old article and I guess it would be nice to include whatever Intel is bundling too. Reply
  • kepstin - Wednesday, August 25, 2021 - link

    This gets particularly interesting with things like AMD's high-end Ryzen CPUs, where even when not overclocking, a better cooler than stock might let the CPU boost to higher frequencies for longer. (Let alone the noise benefits) But that's so dependent on the particular CPU and case environment/ambient that I don't really know how you could make a useful comparison in a standalone cooler review :/ Reply
  • A5 - Wednesday, August 25, 2021 - link

    The short answer is that they're really bad. Anyone who sits in the same room as their computer should invest the $20-$50 to get a good air cooler. Reply
  • TheinsanegamerN - Wednesday, August 25, 2021 - link

    They're fine as long as you dont put a K SKU with unlimited turbo under them. Regular intel chips are quite efficient. Reply
  • Spunjji - Friday, August 27, 2021 - link

    I've never had a good experience with an Intel stock cooler, but I know a few people who've used them for their budget gaming systems. It depends a lot on your sensitivity to noise. Personally I hate the buzzing noise the fans on them make, even at lower speeds. Reply
  • Leeea - Wednesday, August 25, 2021 - link

    I like the pre-applied thermal paste, great feature.

    I wonder if the different fan was necessary, or if they are just artificially nerfing the product? I doubt they cost any different to manufacture.

    I did not know Noctua normally welded the fins, interesting.
    Reply
  • DanNeely - Wednesday, August 25, 2021 - link

    The cheap model has fewer heat pipes and poorer connections between the pipes it does have and the fins. With an equivalent fan it would preform hotter than the more expensive model; to keep the thermal performance the same Noctua used a faster - and thus louder - fan. Reply

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