Top Tier CPU Air Coolers Q3 2015: 9-Way Roundup Review
by E. Fylladitakis on July 6, 2015 8:00 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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zodiacfml - Tuesday, July 7, 2015 - link
Someone should test for this. It is quite plausible as it will take time to increase the temperature of water/coolant in the system. Yet, for longer and continuous loads, surface area matters to dump heat in the environment which AIO coolers has less to a similarly priced Big Air cooler which shows in benchmarks.Navvie - Tuesday, July 7, 2015 - link
Pretty good.It'd be nice if there was a base line (say intel's current stock cooler) and an AIO water cooler to show the difference between a top tier air cooler and what many consider to be the next step.
One point, SPCR always test each cooler with a 'reference' fan, making it easier to compare the heatsink's efficiency. Can't help but feel you didn't complete the task you set out to by levelling the playing field with your simulated CPU heat source.
maximumGPU - Tuesday, July 7, 2015 - link
Great roundup! i for one still believe high end air a good alternative to water if you want dead silence.What i still can't understand is how can Nocuta get away with shipping the most expensive air cooler, likely to be used by enthusiasts who care about aesthetics, with the most hideous fan colours?
'nar - Tuesday, July 7, 2015 - link
Noctua colors are odd, but I think it forces you to consider performance more than aesthetics. They do look nice, but not "cool" - no pun in tended.Dead silence basically depends on how much heat you need to dissipate, temperature of ambient air, surface area of fins/radiator, air flow, and heat transfer capability of the cooler. Or more basically, how easily you can transfer heat from CPU to the air. Water increases the efficiency of heat transfer, so once you reach a certain power level they will overtake HSF's. They will never be as quite as a good HSF, at least not on low-power CPU's that arguably do not need anything but the stock cooler to begin with.
xthetenth - Tuesday, July 7, 2015 - link
Noctua gets away with those colors entirely because they're Noctua. Yes they're not pretty colors, but unlike nice bright/garish colors they are an unmistakable sign that they're the best or at least tied for best.piroroadkill - Wednesday, July 8, 2015 - link
Your keyboard seems to have a problem, you've typed "hideous" when clearly "fantastic" would be better. Noctua fans are neat.Beaver M. - Wednesday, July 15, 2015 - link
Well, serious people are more likely to buy Noctua anyway. And no serious user cares about what the fans look like, and even if they did, they would still take the Noctua, since you can CLEARLY see the extremely high quality they are just by looking at them. Windows in cases and other stupid bling bling is for the PC-ricer gang. They only choose after looks anyway, and dont care if their fans make noises from day one.PrinceGaz - Tuesday, July 7, 2015 - link
Excellent review of what seem to be very good HSFs throughout (but then again, you did ask them to send their best).A comparison with the stock Intel cooler as supplied with something like the 4790K would be nice, as that is what any expense on a third-party cooler must be compared against. How would the stock-cooler compare at 340W? I was very impressed with the degC/W figures for all those coolers; it almost makes 340W seem an amount of heat that can be dealt with, though I'm thinking it's crazy.
As well as the stock-cooler from a highish end CPU, one or two commonly used AIO liquid-coolers needs to be added to provided a second comparison point, as these high-end air-coolers are presumably expected to be near, possibly even better than a liquid AIO.
I love the fact you are using a properly designed heating rig, and your comprehensive review, but I came away thinking: they're good! But I've no idea how much better they are than the stock cooler, or how any of them would compare with the liquid AIOs also available, both in terms of cooling or noise.
Sivar - Tuesday, July 7, 2015 - link
This is probably the best CPU cooler article I've read (and I read such articles when Anandtech when it was on Geocities).Excellent writing, useful measurements, and a cogent conclusion. Thank you, Emmanouil!
orangesky - Tuesday, July 7, 2015 - link
SilentPcReview just posted a review of the new Scythe Ninja 4: http://www.silentpcreview.com/article1462-page1.ht... The review includes some good comparison tables with many of the popular air & water coolers.Sounds like a pretty decent option, and probably the best Ninja since the original.