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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  • m3city - Friday, February 9, 2024 - link

    It would be great if charts included thermal & noise values for a reference (stock) air cooler. This is what holds my wallet in my pocket - I don't know what I will achieve with addition of a water cooler. Less noise?
  • back2future - Friday, February 9, 2024 - link

    [ improved (lower) heat resistance value from cpu&metalShielding towards ambient surroundings air (without additional case fans), therefore (probably, mostly) lower rpms from (2-)3 cooler fans or more headroom for power demand with a water pump providing sufficient flow for the water liquid (and enough surface area for the metal to water heat exchanger on top of the cpu), additionally one could add other sockets or chipsets or storage cooling demand to one cooling system, for the cost/price its about a decision for ~$15-20 quality fan(s) or a water cooler system (this) ~$120, durability comparison? ]
  • back2future - Monday, February 12, 2024 - link

    ['Most CLCs are copper blocks and aluminum radiators. Replacing the coolant in a mixed metal loop with just distilled water will probably result in corrosion issues before too long.' (?)
    'https://www.overclock.net/threads/how-long-is-the-... '
    'https://gadgetmates.com/understanding-the-lifespan... ' ]
  • back2future - Monday, February 12, 2024 - link

    [ mean heat resistance for liquid coolers (tested on anandtech.com) is ~1.5 lower (for average mean) ~0.08°C/W and at ~38-40db(A) sound pressure level ('https://images.anandtech.com/doci/21211/TRvsSPL.pn... ') compared to direct air fans at ~0.12°C/W and ~34-36db(A) ('https://images.anandtech.com/doci/21231/TRvsSPL.pn... '), results to an increased temperature level (for that 100W tested steady heating power) of ~12°C (vs. 8°C for liquid cooling systems) for ~each 100W heat dissipation from cpu and above ambient temperatures and probably more additional resistance with getting into increased temperature levels (sooner with directly connected air fans with heated ambient air building up with slowing reduction rates for higher air flow rates on reducing heat transfer resistance 'https://en.wikipedia.org/wiki/Heat_sink#/media/Fil... ') and that's where the radiator's area advantage for liquid coolers (and) outside the pc case (positioning) adds to silence advantage and heat transfer headroom.

    maybe like that: 'idling'-dominated systems might prefer direct air cooling with fans and 'full-load'-dominated systems can be improved by liquid cooling (above ~~100s Watt power demand) ]
  • back2future - Wednesday, February 14, 2024 - link

    [ just another POV for comparison for air 'direct' on-site and AIO water cooling systems, with a win for on-site air cooling fan (double fan Noctua NH-U12A, ~$99)
    'https://www.youtube.com/watch?t=515&v=23vjWtUp... summary min8:35' ]
  • edzieba - Monday, February 12, 2024 - link

    With a giant glowing RGB brand logo right in the middle of the block, this must be some novel new definition of "Subdued Minimalism" that I was not previously aware of.
  • bwj - Tuesday, February 13, 2024 - link

    SPL isn't a terribly informative way to measure noise. I stopped using a Be Quiet! Pure Loop AIO because although it has a very low SPL, the sound it does make has a high Q factor around its central frequency. It is clearly audible as a whining sound from anywhere in the room, regardless of the power demands on the CPU. It makes that AIO useless for people who wanted a quiet system.
  • back2future - Wednesday, February 14, 2024 - link

    [ What's the frequency (spectrum, sound power)? Some tell recognizable sounds is mostly about air within the pump side from possibly permeated cooling liquid over years of duty (and maybe corrected with refilling cooler liquid and more optimized positioning for radiator inlets being on higher height level than the liquid pump)? ]

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