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 only manually. Fans can have significant variations in speed from their rated values, thus their actual speed during the thermal testing is being acquired 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 Corsair H150i Pro RGB Testing Results, Maximum Fan Speed
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  • FireSnake - Thursday, August 16, 2018 - link

    Nice review, thanks! Reply
  • Orange14 - Thursday, August 16, 2018 - link

    So I can pay over $150 for a liquid cooler that will not out perform top of the line air coolers that are half the price or less. This is the height of madness. Reply
  • mkaibear - Thursday, August 16, 2018 - link

    That's not entirely true - there's still a measurable and significant (>10%) difference between this and top end air coolers.

    Top end air coolers approach 0.1 C/W but this manages 0.07, for example.

    It's not worth it to me, I'm happier with a high end air cooler every time - but for those who like running their systems on the edge for whatever reason there is a difference.
    Reply
  • qlum - Thursday, August 16, 2018 - link

    from what I understand tower coolers can start to rise in resistance when the the load exceeds the capacity of the heatpipes. Until that point they can be fine. They also depend more on the case than aio's.

    Or at leadt so I heard.
    Reply
  • Gasaraki88 - Thursday, August 16, 2018 - link

    Really? You got all that from this review? Reply
  • Stuka87 - Thursday, August 16, 2018 - link

    In my experience to get a standard heat/sink fan cooler to beat an AIO you have to run them at very high fan speeds which also makes them very loud. Plus the AIO's get the heat out of the case, instead of just pushing it around inside. I switched to an H100i 4 years ago and it has been flawless. You can't hardly hear it running, and keeps my 4.5GHz 4690K plenty cool (In the 40's most of the time). If you are going to come here and make claims, its best to have data to back up what you are saying. Reply
  • Orange14 - Thursday, August 16, 2018 - link

    There is alot of data collated over on Overclock.net Most of the issues seen with overheating are a function of inadequate airflow irrespective of whether one uses an AIO or air cooler. Air coolers don't face pump failure with is an issue with AIOs. Large twin fan air coolers run quiet. The one thing AIOs have is that they don't put stress on the MB which is only an issue with shipping computers. For those are DIY builders there should be no difference between AIOs and air coolers if they properly address case airflow. Reply
  • Shlong - Thursday, August 16, 2018 - link

    I have an AIO (generic Asetek 120mm) that I purchased 8 years ago in 2011 for an i7 2600K and it's still working fine. I purchased 3 more since then from Corsair, NZXT and haven't had any issues yet. The systems run quietly when fans would usually be noisy at full load and the ambient temperature in the case is lower. Reply
  • Shlong - Thursday, August 16, 2018 - link

    7* not 8* Reply
  • Icehawk - Saturday, August 18, 2018 - link

    Ditto, have an H80 on a 3770 from 6-7 years ago runs perfectly and silently with a good O/C. Got another one for my 8700 and it’s not quite as silent but better than a tower would be. Cost is the main thing and I can afford the price differential. Reply

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