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 Cooler Testing Results
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  • meacupla - Wednesday, August 9, 2023 - link

    Direct touch heatpipes have their downsides.The heatpipes need to make even contact over all the hot spots to be most effective. On Anandtech's test bench, this downside is unlikely to show up. This is more likely to happen on AMD chiplet CPUs, where the hot-spot is off-center.
  • mode_13h - Friday, August 11, 2023 - link

    If AMD had brought their vapor chamber IHS to market, that should virtually eliminate hotspots, making direct-touch heatpipes ideal. It'd be just like we see in high-end GPUs that integrate vapor chambers, and we all know how much heat those can dissipate!
  • charlesg - Wednesday, August 9, 2023 - link

    I have a Noctua on my 5950X. Very pleased with it.

    Their customer service is out of this world, too!

    At one point I wanted to add more memory to my system, only to find out the pipes from the cooler were in the way. So I emailed them.

    They sent me a new bracket that would allow me to have the pipes a different direction. From Germany. Complete with shipping notification in German. For free!!!
  • Samus - Thursday, August 10, 2023 - link

    I've had my D15 since ~2015 and recently had to have them send me the bracket for socket 1700. They did so 2-day mail for free. I still have the original 120mm fans on it too. I cleaned them when I rebuilt the PC with the new board\CPU and they still work perfect. The D15 and my PCP&C power supply are the oldest components (my PSU is even older - from 2008) and they still work.
  • Threska - Tuesday, August 8, 2023 - link

    "Modern, high-end CPUs will essentially will turbo as hard and as long as their cooling systems will allow, making sustaining those clockspeeds critical to getting the best performance out of a system."

    Increase chances of a crash as well. Some being the silicon lottery.
  • mode_13h - Tuesday, August 8, 2023 - link

    One benefit you supposedly get from buying Xeon CPUs is that they are qualified with extra margins, to ensure stability.

    Since I can no longer afford any of the Xeons or the platform they require, I will try to get by with running a mainstream Core-series CPU on a restricted power budget. And ECC RAM, of course.
  • Sivar - Wednesday, August 9, 2023 - link

    You can always use an AMD CPU. In this generation, their CPUs use half the power. Intel is now playing the old AMD game of overclocking their own CPUs to ad absurdum just to keep up with their competitor.
  • blzd - Friday, August 18, 2023 - link

    DDR5 has built in ECC on consumer level I believe.
  • tygrus - Monday, August 21, 2023 - link

    Standard DDR5 has ECC on chip protecting from random 1bit per byte flips while data is at rest. It doesn't cover the signal integrity between CPU & RAM.
    Reg ECC DDR5 for servers provides the extra protection of data in transit in addition to protecting data at rest.
  • mode_13h - Thursday, August 24, 2023 - link

    @tygrus, you mention "Reg ECC DDR5", but it's also available unbuffered.

    The main downside of ECC DDR5 DIMMs is that you now need 25% more DRAM chips than non-ECC, due to the bifurcation of the DIMMs into 2 32-bit subchannels, yet each still having 8 bits of ECC.

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