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


View All Comments

  • PeachNCream - Saturday, June 20, 2020 - link

    Calling someone a troll when there is no trolling happening is usually one of the last lines of defense by means of attack a person with a computer tech interest and insecurities about said interest makes in order to invalidate information they do not want to accept. Usually someone in that mindset also ends up posting prices of their computer hardware eventually in order to cloak a bragging session about what they spent as a portion of some reasonable (to them at least) way of explaining something. I see you've done that second part as well, Mister Skywalker. Reply
  • BenSkywalker - Saturday, June 20, 2020 - link

    I'm going to go into a discussion about a water cooler to trash water coolers and that isn't trolling...? If this were an air cooler you would have a point, but alas.

    I was accused of trying to justify my purchase, the point of listing prices is simple- there is *ZERO* justification for any of it and more importantly, I don't need to justify anything to anyone excerpt the wife.

    Last line of defense?

    Water is cooler, water is quieter.

  • Dug - Tuesday, June 23, 2020 - link

    What you don't understand about sound is that decibels are not the deciding factor for most people on whether they care about the noise. It's the frequency and vibration. And pumps are some of the worst for annoying people. Just like a mosquito isn't loud, but it is annoying. That is why you will see so many threads about pump noise, even if fan noise was higher in decibles on their system. To say that pumps are quieter than slow moving fans is fanboyism at it's best. There is no possible way due to how fast a pump spins with water running through it. Reply
  • BenSkywalker - Tuesday, June 23, 2020 - link

    Citing hard data is "fanboyism".....?

    You saying pump noise is on a frequency you find more annoying is one thing, louder is a hard data figure and the numbers say I'm right.

    I can only assume those complaining about pump noise are basing it off of some custom loop using a junk aquarium pump from years ago.

    Also, you do realize that modern AIOs have variable pump speed, right? I'd assume most of them even let you adjust the ramping(the ones I've used do).
  • BenSkywalker - Friday, June 19, 2020 - link

    My radiator and all its accompanying fans are behind the tray my motherboard is mounted to. Pump noise is some interesting FUD I hear from the never so much as seen a water cooled setup in my life crowd, but the fans are *much* louder than the pump in every setup I have ever seen, they pale in comparison to the noise created by air cooling.

    So, show me an air cooled setup where I can mount the tower remotely so I can have a clean appearance? You up to it?

    Justifying the expense....? So it isn't the $300 I spent on a case, the extra $100 I spent for Royal RAM over regular RAM, it isn't the $1300 I dropped on a 4k/120HZ GSync monitor or the $1300 graphics card, it isn't the $500 I spent on my DAC/Amp/Cans or the $250 I spent on my mouse and keyboard, no, what I need to justify is the extra $75 for a water cooler over air.......

    We have a frivolous hobby. As much as I spent building what most people think is an insanely over the top setup, it still cost quite a bit less than my buddies rims he just bought, or a couple of days vacation time with the family, he'll the gap between air and water is a small Friday night bar tab.
  • Beaver M. - Saturday, June 20, 2020 - link

    Water is FAR noisier.
    I dont hear my D15 at all. AT ALL.
    I could still increase its RPM if needed, or add another fan (only running 1) and still be far more silent than any water system Ive ever heard.
  • BenSkywalker - Saturday, June 20, 2020 - link

    Sound measurements are done, articles linked. For the same level of cooling water is quieter. That doesn't mean you can't build a quiet air setup, it just means at the same noise level water would run cooler. Reply
  • Beaver M. - Wednesday, June 24, 2020 - link

    Where are you putting your microphones then?
    The pump or the radiator fans? Huge difference.

    You cant reach the cooling custom water has with air coolers, no matter what. So such a comparison is nonsense in either way.
    Only AIOs are comparable. And they are FAR noisier than air.
  • BenSkywalker - Wednesday, June 24, 2020 - link

    I linked to air, this article has AIO numbers, air is louder. It's a safe bet all of using water have a lot of experience with air.

    Mic is normally placed roughly one meter away although it varies based on the person testing it is almost always noted.

    AIOs are quieter than air.
  • JimRamK - Wednesday, June 17, 2020 - link

    If you're using an SFF PC, a CLC or other liquid cooler may be the only way to get excellent cooling since the best air coolers are fairly tall and need a full sized case. Reply

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