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 Phononic HEX 2.0 Thermoelectric Cooler & Software Testing results, maximum fan speed (12 Volts)
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  • saratoga4 - Monday, September 26, 2016 - link

    >Note that a large percentage of this energy consumption is inserted as additional thermal load for the cooler to dissipate.

    All of it should show add to the air cooler load. Energy is conserved.
  • ImSpartacus - Monday, September 26, 2016 - link

    This is one of those times where you're reminded why coolers use the tech that they use. It seems to be tough to beat.

    Good review though. Always interesting to see new things.
  • LordOfTheBoired - Tuesday, September 27, 2016 - link

    Honestly, in this case it seems like poor design decisions.
    They went with an unusually small fin stack, and thus unusually limited heat dissipation area, for a cooler design that needed to dissipate more heat than the norm.
  • evilpaul666 - Wednesday, September 28, 2016 - link

    I was surprised to see this review when I popped in today. I'd recently remembered the TECs of the early 2000s and wondered, "Whatever happened to those?" Back in the day they were too expensive and poorly controlled so condensation was a serious risk.

    The latter seems to be addressed by this product, but having just picked up an AIO 480mm water cooling solution for slightly less money than the older ones I looked up that were still listed on Newegg/Amazon this one is still a bit more expensive although it solves the MASSIVE heatsink that won't fit into most cases problem that older TEC solutions had. Possibly to its detriment as the performance doesn't scale great. That might be fixed by different design decisions like you mentioned.
  • Demi9OD - Monday, September 26, 2016 - link

    I ran a TEC with a water cooler way back in the day on my Pentium 3. Condensation was awful, I needed a catch under my CPU for the dripping water.
  • BrokenCrayons - Monday, September 26, 2016 - link

    I had severe condensation problems with a TEC cooler I purchased at a computer show on an AMD K6-3. It didn't ruin the motherboard, but when I pulled the cooler off to check on things after running one for a couple of days the trench around the rim of the heat spreader was filled with water and the underside of the chip was damp. It didn't offer any additional overclocking headroom either, which was what I purchased it for to begin with. It was a 400MHz chip and I never got it to reliably hit 450. After discovering the condensation, I popped my cheap air cooler back on the chip and never looked back.
  • Samus - Monday, September 26, 2016 - link

    Alas, I had condensation issues with my peltier/liquid cooling on my Athlon slot-A which left some options to address over a socketed CPU, but still did something dramatically different to address it.

    I moved the peltier to the water reservoir, installing a heat sink/fan on the peltier. The water reservoir was made of copper so the chilling effect conducted well and this dropped the water temperatures to sell below ambient.

    This system worked awesome for a long time until one day my water pump failed. Yep, the water got so cold it froze. I didn't out antifreeze or anything in, opting for wetter water instead because of its better high temp properties.
  • Marlowe - Wednesday, September 28, 2016 - link

    Samus: That's actually really smart. Although in retrospect you should've applied some antifreeze :-) In what way do you think can a modern AIO water solution incorporate a peltier element?
  • Bigman397 - Friday, September 30, 2016 - link

    A new class of AIO cooler that has an external reservoir/fin stack with a peltier? Seems like an interesting idea. I always figured if I went to the lengths of making a big custom watercooler set I would use a multi-loop system with a heat exchanger, obviously ridiculous in a practical sense but fun to theorize.
  • Stuka87 - Sunday, October 2, 2016 - link

    Another option is to have the peltier on an adjustable voltage slope. When the CPU is idle, it doesn't do much. But as temps increase, it too increases. That way you kind of have the best of both worlds.

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