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, with the ability to vary the load, as the thermal resistance also varies depending on the magnitude of the thermal load. Therefore, even if it were 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 very 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 or compatibility. The thermal cartridge inside the core of our testing station can have its power adjusted between 60W and 340W, in 2W 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 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, we're measuring these manually. Fans can have significant variations in speed from their rated values, thus their actual speed during the thermal testing is acquired via a laser tachometer. The fans (and pumps, when applicable) are powered via an adjustable, fanless desktop DC power supply and noise measurements are being taken 1m 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.

Noise Level Reference Values
<35dB(A) Virtually inaudible
35-38dB(A) Very quiet (whisper)
38-40dB(A) Quiet (slight humming)
40-44dB(A) Normal (humming noise, comfortable level)
44-47dB(A) Loud* (strong aerodynamic noise)
47-50dB(A) Very loud (strong whining noise)
50-54dB(A) Extremely loud (level equivalent to a ≈1500W vacuum cleaner)
>54dB(A) * Intolerable for home/office use; special applications only.

* Noise levels above this are not suggested for daily use

Silverstone Testing Results, Maximum Fan Speed (12V)
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  • Laststop311 - Wednesday, February 12, 2014 - link

    noctua d14 runs cooler and quieter. These all in 1 coolers all suffer from the same problem. The pumps used are cheap loud and not very powerful. You need to build you own water cooling loop using high quality waterblocks radiators pumps and tubing then and only then can u take the noctua d14 down, And I'd still use high static pressure noctua fans on the custom water cooling loop because noctua fans are awesome
  • theNiZer - Wednesday, February 12, 2014 - link

    E. Fylladitakis : I like the theme of the article and the approach, BUT did you use the same fan-type for all coolers? If not, that explains the lov efficiency of Coirsair H105 - it has more low noise tuned fans.
    You should test the units with the same fan as well to really tell the effect of the individual watercoolers.
  • E.Fyll - Wednesday, February 12, 2014 - link

    No and I will never use any other fan than the ones supplied with the kit. I explained why thoroughly in the comments above. I cannot perform tests with a fan of my choice, as the characteristic performance of the said fan will favor some designs over others, creating misleading results. And I cannot possibly perform testing using dozens of fans either.

    It also increases the cost. Most people simply want to buy a cooler, not half the store. If someone wants to use different fans for whatever reason, I cannot possibly foretell how each kit will react. RPM, CFM, sound pressure levels are all next to irrelevant when a fan is going to be mounted on a heat exchanger, therefore any comparisons between fans that "look similar" are a massive mistake.

    I performed noise testing, you know. If you would look at it, it is one of the noisiest kits in the roundup. So that could not have been further from the truth.
  • Hxx - Wednesday, February 12, 2014 - link

    Why no thermaltake? I managed to snag a thermaltake performer 2.0 from Microcenter for $5 after a rebate lol last BF. It was too good to be true. They also had the extreme 2.0 for $35. Great cooler too (both of them although i kept the little one).
  • E.Fyll - Wednesday, February 12, 2014 - link

    Copy-paste from above:

    "I know. I actually tried to acquire all AIO coolers in existence, including Intel's, Thermaltake's and others. Not everyone is happy to cooperate and/or willing/able to supply samples at a give time, for whatever reason."

    I cannot test what I cannot have access to.
  • Dizey - Wednesday, February 12, 2014 - link

    I normally don't comment, but I just have to say that I'm also really disappointed that the Swiftech H220 isn't in this review. In all fairness, one could argue that the H220 isn't a close loop cooler, but the lack of its presence in this article does give it a fowl stench.
  • E.Fyll - Wednesday, February 12, 2014 - link

    Copy-paste from above:

    "I know. I actually tried to acquire all AIO coolers in existence, including Intel's, Thermaltake's and others. Not everyone is happy to cooperate and/or willing/able to supply samples at a give time, for whatever reason."

    I cannot test what I cannot have access to.
  • Dustin Sklavos - Wednesday, February 12, 2014 - link

    The H220 isn't *available.* Asetek's litigation means you can't buy it stateside, rendering its performance somewhat irrelevant.
  • twtech - Wednesday, February 12, 2014 - link

    I don't see a winner listed, but the results seem to say that, from a performance standard, if you have the room to fit it, the Corsair H110 is what you'd want to buy. It's basically a close 2nd in both performance and noise, which makes it a clear #1 overall.
  • twtech - Wednesday, February 12, 2014 - link

    And by standard I meant standpoint.

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