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 SilverStone Permafrost Series AIO Coolers Testing Results, Maximum Fan Speed
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  • close - Thursday, June 18, 2020 - link

    On topic: I'd still go with air on any system I plan to keep for a while. I have plenty of machines still operating just fine after close to a decade, I don't want to tempt fate with a liquid loop.

    Off topic, Germans don't seem to believe in A/Cs mounted on the outside of every building and the A/C noise that all neighbors have to live with. And I remember years ago my neighbor's A/C unit (not in Germany) keeping me awake at night because that hum and vibration would be heard and felt best in my bedroom. Also Germany wasn't the hottest, most humid of countries when they came up with the policies.
    Reply
  • PeachNCream - Thursday, June 18, 2020 - link

    Seattle has that same sort of problem. It only gets hot enough to really warrant AC a few weeks out of the summer during a typical year so most residential construction and some business structures lack air conditioning. The only time its a problem is for those few weeks of summer and when there is an unusual heat wave, but while living there, the point of keeping a PC that doesn't generate a lot of heat or require extensive cooling was sort of reinforced. My desktop made my bedroom feel warmer but my netbook was insignificant. It should be no surprise that I figured out how to stay connected, amused, and busy on just an Atom n270 at that point. :) Reply
  • khanikun - Friday, June 19, 2020 - link

    I normally just go air for my non-main rig. One is a file server and just sits there, while the other is a backup gaming rig. That one usually just sits there too and I play videos on it, while gaming on my other machine.

    I think AIOs are fine, so long as you aren't constantly tinkering around in your machine. The more you mess with it, the more likely something on it might fail and cause leaking. Why I have them in my computers that I don't mess with much and have a custom on my main rig. The custom is a much more robust setup.

    As for Germans and A/C, ya. They didn't bother with it, since it really wasn't all that hot and didn't last long. A fan would suffice, but with everywhere being hotter nowadays, people are definitely rethinking it. The last 3 years I was there, every summer the portable A/C units were sold out for the whole season. Peak heat only lasted like 2 weeks, then over time that changed. Went from 2 weeks to a month. Then a 1 1/2 months. Was also getting close to 100F.
    Reply
  • Slash3 - Thursday, June 18, 2020 - link

    I love how the top two best results in every graph on that page are air coolers. Reply
  • Slash3 - Thursday, June 18, 2020 - link

    Haha, hoist by my own petard. They're all air coolers in those graphs. Reply
  • Flunk - Monday, June 22, 2020 - link

    Not really, it's just dependant on the size of the radiator. AIOs can be made with later radiators than tower coolers, but it doesn't make AIOs magically better. It's just a matter of how much heat dissipation surface you have. If you get the heat there with heat pipes or pumped liquid is largely irrelevant. Reply
  • hansmuff - Wednesday, June 17, 2020 - link

    Repeat after me: there are other benefits and they are worth it to some. Reply
  • eek2121 - Wednesday, June 17, 2020 - link

    Baseless argument. I have been using AIOs for a long time and have never had a leak. One of my units is 6 years old and is used daily. Reply
  • WaWaThreeFIVbroS - Wednesday, June 17, 2020 - link

    That doesn't mean others never had their AIOs leaked, my AIO leaked and broke the GTX 980 beloe it, never again Reply
  • PeachNCream - Thursday, June 18, 2020 - link

    A single digit sample size does not make for reliable data on a statistical level so claims either for or against leak risks would really need a broader collection of data than we have the ability to gather here. That's why I don't really comment much on leaks aside from pointing out we haven't the right information. As far as I'm concerned, other more obvious factors are worth consideration beyond leaking or not leaking (though I do feel for someone losing expensive hardware due to a leak - kinda sucks). Reply

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