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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marraco - Monday, July 6, 2015 - link
Something really important that never is reviewed is dust control and maintenance.As radiator fins get closer, they have more dissipation area, but air flow gets worse. Yet the main problem of fins closeness is that they accumulate dust much faster, and get occluded.
No review makes a dust test. I have a Thermaltake cooler, which works excellent when is clean, but it rapidly loses his capacity due to being occluded by dust.
The easiest way to remove his dust is to use canned air, but it is a short lived fix, because an air cleaned radiator occludes itself very fast, sometimes in matter of weeks.
The only way to clean it for good is to take out the dissipator, and put in in the dish washer. But that is a cumbersome task. I need to do a lot of work just to clean it, and I need thermal paste to place it again on the motherboard.
So, maintenance is as important as cooling and noise.
A good cooler should pass a dusting test (being exposed to a day of dirty and dusty air current), and should be possible to clean it without much hassle, without applying thermal paste, without using screws, without need to access both sides of the motherboard, and without his pegs breaking or being degraded by manipulation.
'nar - Tuesday, July 7, 2015 - link
Interesting concern. It makes sense, yet is never considered. I think the best answer is the same as electricity, you need to provide the best environment you can for your computer. Higher quality components are more sensitive to dirty power, and dusty air. Get that PC off the floor, and get a case with good dust filters. And if your room is bad enough, get an room air filter. I have one on my desk right in front of my PC. A Honeywell HEPA air filter.Impulses - Monday, July 6, 2015 - link
I understand why cases are tested with stock fans, replacing 3+ quality fans will significantly alter the price equation... It's a trivial difference for $50-100 heatsinks tho, many are often even sold sans fans anyway.If nothing else, a single apples to apples test with all running the same fan would've been welcome. In addition to something like the Hyper 212 as a baseline, the different Thermalright TRUE Spirit variants have remained a solid value over the years (they perform better than the 212 and even closer to some of these as per HardOCP's last roundup).
Is there gonna be a midrange roundup? Spending upwards of $65 on an air cooler never made much sense to me when more affordable options were so close in both noise and performance. Out of 9 coolers tested only 3 or so come in at a sensible price, at $75+ wouldn't it make more sense to go AIO WC?
xthetenth - Monday, July 6, 2015 - link
If you want low noise, good thermals and dead quiet idle well into the land of diminishing returns, high end air is still a very compelling alternative to water, especially if you're willing to put the effort into some ducting.However midrange products can be excellent and are well worth a good long look before hanging a hundred bucks off your socket.
'nar - Tuesday, July 7, 2015 - link
I was a HSF fanboy until I actually needed a water cooling system. Specs and testing does not show response time. Fast, transient loads can overwhelm a HSF, as heat pipes cannot transfer heat as fast as water. For low power CPU's a HSF is fine, but when you go over 100 watts the noise is less of an issue, as a HSF will need much more airflow to compare to the higher heat transfer ability of W/C. And instantaneous loads are more likely to cause system instability due to the less efficient heat transfer rates of heatpipes.meacupla - Tuesday, July 7, 2015 - link
I am going to nitpick on what you're saying there, because you have it confused.Heatpipes use some form of vaporized liquid inside and they actually transmit heat quite good, especially when compared against sold copper rods. Where they fail, is that they do not have a lot of capacity for transferring large amounts of heat.
Water is actually quite poor at transmitting heat, as it's a non-metal and an insulator. It does, however, have great capacity to hold heat.
This is why large bodies of water are warm during winter and cold during summer and results in mild weather near the coast and extreme weather in the interior.
The advantage of water cooling systems, over air cooling, is the ability to place large radiators, with a lot of surface area, in spots that get fresh air from outside the case, instead of warmed up air that is already inside the case. Heatsinks are also limited to size and weight constraints around the socket.
Were it possible to attach a triple 120mm fan heatpipe heatsink, as in parallel layout, instead of serial dual towers, directly to the CPU, I'm quite sure the results would be similar to a 360mm radiator water cooling setup.
xthetenth - Tuesday, July 7, 2015 - link
Yeah, he's describing the thermal mass of the coolant, not any transfer capability. It seems that running coolant through radiator fins does have an advantage of relying on the fins to radiate the heat out from a heatpipe, but for a similar surface area, it's questionable how large the advantage is, especially at CPU TDPs.GPUs on the other hand have a more constrained form factor for large air cooling and a higher TDP, so they are a more promising place for CLCs.
PitneFor - Monday, July 6, 2015 - link
wheres Prolimatech, my precious...mejobloggs - Monday, July 6, 2015 - link
I'd be very interested to see a size-per-performance chart.I usually buy coolers that perform the best without being too large. Although I guess "Top Tier" coolers isn't the right article to look for smaller size coolers :p
Impulses - Monday, July 6, 2015 - link
Leaving it to the manufacturers to select their entry is always messy or questionable IMO, TR choosing the Macho over the Silver Arrow for one... Still curious whether there's a midrange round up planned or if this is it for air coolers at AT for a couple more years...Despite the criticism I do appreciate E Fyll's thorough process, otherwise I imagine I and many others wouldn't even bother commenting. Low end (212+) and high end ($120 AIO?) base lines would make the article much more useful tho.
The into even suggests some people prefer high end air over WC at the start but then leaves that up in the air... No pun intended.