The Alphacool NexXxoS Cool Answer 360 DDC/XT Liquid Cooling Kit Review
by E. Fylladitakis on October 24, 2016 9:30 AM ESTTesting 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
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Death666Angel - Tuesday, October 25, 2016 - link
That works for people hard of hearing, those willing to put up with abysmall thermals and/or loud noise or those like you who have enough space and willingness to put the source of the noise in another part of their dwelling.BrokenCrayons - Tuesday, October 25, 2016 - link
That's a lot of exaggeration. Stock coolers are ear-splitting monsters that let the chip run at unsafe temperatures. There are literally billions of PCs that have been shipped with OEM coolers over the years and while a few designs have been fatally flawed (I'm looking at you ECS GREEN320 laptop with your whiny hair dryer blower on a 1GHz VIA C3 processor) the vast majority of them provide years of problem-free service by keeping the CPU within manufacturer specified temperature limits without causing undue end user stress due to poor acoustic design.Keep it in perspective. I'd happily agree that temperatures might be lower and the computer might be quieter with a bit of attention paid to cooling, but the way you're putting things seems overly dramatic.
HollyDOL - Monday, October 24, 2016 - link
I moved to custom loop to get rid of "angry vacuum cleaner" (back in 8800GT days). My pump is sitting in a foam inside the case and radiator is external, passive and quite big. In combination with noise dampening case and semi-passive PSU it's silent at city night (I guess in significantly quieter environment you could hear a bit but not really much).galta - Monday, October 24, 2016 - link
Liquid cooling is for people for want/need extreme performance, generating tons of heat in the process. Heatsinks that come out of the box cannot handle it.There is also the question of noise, for cooling an OCed system on air produces - generally - more noise than on liquid.
Those, however, do not seem to be circumstances that apply to you, so you better stay on air.
JoeyJoJo123 - Monday, October 24, 2016 - link
I'd clarify the "generally" part as follows:If they're using an AIO, chances are the combined pump + fan noise is actually noisier than a dual stack tower heatsink. (2x 120mm or 140mm fan + pump noise VS 2x 120mm or 140mm fans and no pump).
If they've built a custom open loop, then chances are that they've over-engineered the solution (as the few who go this route have the cash to spend and are willing to go all the way) and are using a thick radiator, a large reservoir, a large but quiet pump, and fans that don't ever need to spin up to address increased heat on intensive tasks, and at this point, they might actually have a quieter solution.
galta - Monday, October 24, 2016 - link
Lots of chances involved, it seems. In the end, what makes sense - generally - is to understand your problem and look for the best way to solve it.For some, air will do; for others, not.
Check Corsair's H110iGT review @ Guru3d: it is as quiet as the venerable Noctua NHD15, but 9C cooler when overclocking an i7 4790k. Oh, and it also significantly lighter than 1.32kg.
But then there is our friend BrokenCrayons, mixing bunnies with pancakes...
fanofanand - Tuesday, October 25, 2016 - link
I thought his points were valid and reasonable, far from mixing bunnies with pancakes.BrokenCrayons - Monday, October 24, 2016 - link
To steal a certain internet meme, "Overclocking in 2016 makes about as much sense as a bunny with a pancake on its head."Aerodrifting - Monday, October 24, 2016 - link
What's the point of running X99 i7 if you don't overclock? So you can be content with stock 3.0 speed?BrokenCrayons - Tuesday, October 25, 2016 - link
What's the poinnt of overclocking it? The home user's typical workloads don't benefit from overclocking and if they do, the increase in performance is marginal and not worth the effort. Sure there's showboating to friends and emotional self-gratification, but those aren't tangible rewards. If emotional satisfaction is what you gain from that sort of thing, then knock yourself out, but in my opinion, it's wasteful, childish, and silly.