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 Coolers Testing Results
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  • YB1064 - Wednesday, July 21, 2021 - link

    RGB lights to make your eyes bleed. Who is the OEM? Do Silverstone make their own AIO?
  • Scott_T - Wednesday, July 21, 2021 - link

    my next purchase will be a completely light proof case painted internally with ultra black to suck up all the rgb crap I didnt ask for.
  • evilspoons - Wednesday, July 21, 2021 - link

    I have a Fractal Define XL R2 with opaque sides and a front door I almost always leave closed. The only light that leaks out of my case is from my 1080 with white LEDs and it works as a nice little nightlight. (I can't even remember if I left the RGB pattern on my mainboard on, I can't see it.) It's very nice that it just stays out of the way.
  • Samus - Thursday, July 22, 2021 - link

    My Silverstone AIO cooler purchased a few years ago had Asetek hose clamps, so my guess is the entire thing was sourced from Asetek. It'd be a safe guess that this is still the case today, but who knows as this 280 model is a very proprietary-sized cooler and they could have done it in-house.
  • Threska - Wednesday, July 21, 2021 - link

    Well one thing that comes to eye is the ease of installation.
  • Oxford Guy - Wednesday, July 21, 2021 - link

    Which of the models tested have proper static pressure design fans instead of case fans?
  • meacupla - Wednesday, July 21, 2021 - link

    In the article, just above the picture of the fan, it says they all use air blazer fans, which are high flow, low pressure.

    Considering the thickness and fin density of the radiators, I doubt using static pressure fans would make any difference.
  • Oxford Guy - Sunday, July 25, 2021 - link

    I remember a detailed fan testing article from here (a number of years back) that made it very clear that case (airflow) fans are optimal only for very low restriction scenarios and static-oriented designs should be used for restriction, such as radiators. I would like to see a chart that changes the perspective to ‘restrictive scenarios like radiators are fine for case fans if the fins are a certain minimum width’.
  • Oxford Guy - Monday, July 26, 2021 - link

    The gaps between the fins, that is.
  • citan x - Wednesday, July 21, 2021 - link

    Sometimes, I think your testing is too theoretical and not practical enough. I just happen to be looking for a new cooler for my Threadripper CPU and have been looking at reviews. When your article mentioned Threadripper, I though I might see some good analysis on how the size of the cooling block affects cooling performance. Yet, you failed to mentioned this anywhere except for a small blurb in the introduction. Does this mean the size of the contact area does not affect the cooling performance?

    I find this hard to believe cause I have seen other reviews where the coolers made for Threadripper do hold some advantage over coolers that are smaller. I am looking to get good cooling performance at a low noise level. I am trying to figure out if it is worth it to go for the few coolers that are made for Threadripper or to just get one of the top performing AIO coolers. This article however failed to address that.

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