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 Cougar Helor 240/360 AIO Coolers Testing Results, Maximum Fan Speed
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  • dotes12 - Monday, December 9, 2019 - link

    How large is the actual heating element in your thermal cartridge? I'm hoping you're not uniformly heating a square the same size as a typical IHS of a typical Ryzen/Core CPU. The CPU is a much smaller point heat source. This definitely comes into play with AMD using multiple chiplets vs Intel using one large chip on mainstream CPUs, and I think those are important variables you're possibly overlooking.
  • JoeyJoJo123 - Monday, December 9, 2019 - link

    That literally doesn't matter. The idea is that they built a heating element that they can generate a fixed amount of heat, and by doing so they remove extra variables from the equation when testing the HSF to see how it fares from lower to higher heat loads. You don't want to be using actual CPUs which may vary from processor to processor how much heat is generated between microcode revisions (AGESA for AMD or microcode security fixes for Intel CPUs), along with variances in software performance due to updates (stress test updates can affect the expected amount of heat a given CPU would generate) or background Windows/OS tasks, etc. These are all variables that might vary from month to month or year to year and can suddenly invalidate past results/tests.

    Yes, this testing methodology isn't 100% like-for-like in how a CPU + heatspreader's targeted hotspots might perform, but the benefit to doing it this way is that the only variable is the cooler being tested.
  • dotes12 - Monday, December 9, 2019 - link

    ...but it does matter in watercooling because the water flow is directed to specific places.This is 100% perfect for testing passive and air cooled metal heatsinks, don't get me wrong. The size of the heat source makes almost no difference in something that has so much thermal mass. Really all I'm trying to say is that waterblock performance and absolute thermal resistance aren't as simple as 1 number. The problem is that the idea behind a CPU waterblock is to direct the most waterflow and put the most surface area over the hottest part of the chip. Historically that's been a small point heat source in the center of the IHS like with Intel so far. EKWB's jet design are great for those for example, but in the last few years we're seeing AMD use chiplets that aren't even centered on the IHS, so what does that mean for the jet design? I expect that the jet design is a poor choice to use on a AMD chip, but that's all EKWB sells for Ryzen. The heat source location and size is much more important in waterblock design and testing than you're giving it credit for, but this is definitely a good start!
  • E.Fyll - Monday, December 9, 2019 - link

    The heating element is circular, with a diameter of 5mm, placed at the center of the block.

    True, this is not an exact representation of every single CPU. However, it is a reliable way to test any given CPU cooler. Pure copper has a massive thermal energy transfer capacity, which is why it is being used for heat spreaders. The heat spreader of a CPU, thin as it may be, distributes energy extremely quickly. Remember that several Threadripper "adapted" coolers were not large enough to cover the CPU's dies, leaving large parts of the heat spreader exposed to open air, and still would work OK (although their performance definitely was anemic - that is just an extreme example).

    With that in mind, it should not really matter if the point of heat generation is not exactly at the center of the CPU, as the copper plate above the die and the copper base of a cooler should be capable of coping with the energy transfer. Even if an engineer designs the cooler with the primary heat transfer point being at the center of the block, it should perform roughly the same even if the CPU die is moved a little to either direction. If it is unable to, that is a serious design flaw, one that I cannot believe any competent engineer would make.
  • dotes12 - Tuesday, December 10, 2019 - link

    Thanks for the reply! A circular heating element with a 5mm diameter placed at the center of the block is an awesome reproduction of an Intel CPU. I was worried it was spread out further than that, which wouldn't be an ideal test heater. Everyone is designing blocks for the point heat source being in the middle, so might as well test them that way too haha
  • jmke - Tuesday, December 10, 2019 - link

    test setup is good to give you an idea of the cooler capacity.
    case layout, installation, airflow etc are also very important factors which are not accounted for.
  • 29a - Monday, December 9, 2019 - link

    I wish they would test more coolers. I have an LC240e that I got super cheap that I would like to see compared with these.
  • eek2121 - Monday, December 9, 2019 - link

    Disappointed at the lack of a TR4 option.
  • tamalero - Thursday, December 19, 2019 - link

    seconding.. No idea why the product that needs the AIOs and watercooling options.. are the ones not getting them.
  • Dragonstongue - Monday, December 9, 2019 - link

    Beyond the price, Cougar Vortex HDB fans are AWESOME

    have quite a few of them, just a wee bit louder then the veritable Noctua Redux, they while usually +/- similar price point (not as tough plastics that Cougar probably should be using given the price normally charged for them) are well worth it, overall.

    had got a Cougar Archon case for my old E8400 EO build that my mom is still using to this day (off and on) while a "budget case" and kind of tight, was overly quite impressed.

    i.e if they offer, I will take a long look at simple as that, they have for my $$$ proven themselves a worthwhile contender compared to say Rosewill who (as an example) have proven themselves (likes a few others) so-so in regards to what they charge, what we as consumers expect, and what we end up getting.

    Cougar is a very good company (subsidiary of or whatever means little, provided they produce good stuff at a fair value)


    as for the below folks...I personally feel that the way AMD is "now" doing with chiplet is a far far better thing than Intel "chasing" so called "monolithic die" which allows AMD to "spread the heat load" over the various chips and powerplane, vs Intel (conversely Nvidia as well IMO) that concentrate the heat in a very small area (which also has the "nasty" of driving power higher than it ought to be as the "chip" has to work that much harder to keep speeds up..inevitably leading to "shortened life span" or requiring that much more / fancier regulation...

    I trust AMD "numbers more" for the most part as "historically" they have stayed AT or Below "rated" TDP numbers (so much easier to get proper cooling to handle it) vs Intel of Nv that seem to use a "looser if not impossible" rating on the box, just to make the sale.

    yes Intel chips were/generally are "easier" to cool, but having that heatload in a much smaller area, really has only benefited THEMSELVES (i.e, keep price to produce lower, therefore they can keep more in greedy pockets)

    I myself would prefer a much larger die to cool vs a stupid small one that goes from cool as cucumber to raging inferno level heat at a moments notice (definite hard on the device, no mater how it is worded, certainly very hard on the motherboard / socket / pcb to also contend with .. certainly the fans trying to expel a mass rush of heat not so easily dissipated, but needs to be rid of ASAP or nasty stuff happens)

    Maybe AMD was right "all along" by "gluing dies" together, far easier to make AND cool properly while not being "all that much" pricier (not to mention cost for motherboard much less socket cost) vs Intel "choice" to use LGA (whatever they call it) which has had loads and loads of problems.

    anywho, I agree on the test style, test the cooler FIRST, then worry about test individual CPU (or GPU) so that variables are "not something to be concerned with" unless one is wondering how it will cool product X Y or Z


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