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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'nar - Tuesday, July 7, 2015 - link
I know right? I was so looking forward to a W/C vs A/C comparison after an intro like that.Margalus - Monday, July 6, 2015 - link
why didn't you test these all with the same fan? Then we could see how the cooler performed independent of the included fans? Like the Thermalright, it comes with no fan, apparently you got a super quiet slow fan and put on there, but that isn't fair to Thermalright saying they are hotter, when it could be because it doesn't have the amount of air moving over the fins as others.Beany2013 - Wednesday, July 8, 2015 - link
Thermalright provided the fan, so they can't grumble at the results.trandoanhung1991 - Monday, July 6, 2015 - link
When you talk about ultimate cooling, you should've at least tested the True Spirit 140 Power Edition with a TY-143 fan, or the Silver Arrow SB-E Extreme. Those are the most interesting products from Thermalright, not the Macho Zero.Maybe as an addendum at some point? I'm very interested to see how the Silver Arrow and the 140 PE fare against the D15.
Impulses - Tuesday, July 7, 2015 - link
Apparently the Macho is what TR themselves chose to send AT, if the intro is accurate... Big /facepalm on their part. They probably have some of the best value coolers in the TRUE Spirits (I have the original Cogage version myself), and the Silver Arrow might've ranked up there with the Noctua and Phantek. The article did make me pretty curious about the latter tho, call me vain but the color choices are cool.Calculatron - Monday, July 6, 2015 - link
Thanks for doing a heatsink round-up. They are refreshing to see these days.It is a shame that Thermalright did not send in its top-tier performer. Then again, the Macho Zero is nothing to sneeze at. ~40C over ambient for a 340 watt load is still a good result. (Perhaps, instead, they could have thrown the TY143 performance fan instead? Har!)
siberus - Tuesday, July 7, 2015 - link
I actually wish they would have sent 2 of the current fans so we could see if push/pull could push it up a performance bracket.rrohbeck - Tuesday, July 7, 2015 - link
I'd like to see the measurements all with the same fan(s) - whatever is considered "the best" fan. That would give an indication of how much you could get out of the cooler with aftermarket fans.'nar - Tuesday, July 7, 2015 - link
I wish there was more review cross-over with water coolers, these two camps seem to be at odds with each other. They never seem to be compared effectively to each other, so it is difficult for consumers to determine the "best" cooler for themselves. With Noctua getting up to $93, there are water coolers out there for less. I bought my Noctua NH-D14 for $75 and thought that was high for a HSF.I strictly used air coolers until I got an AMD APU, among them are several Noctua models. It was apparent to me that this CPU, after a bit of easy O/C, got hot much too fast for an air cooler to absorb. It would crash after just 4 seconds of starting Tomb Raider and the cooling fins were still ambient temperature. I tried three coolers including the Noctua NH-D14. Fan speed did not matter as the rapid increase in temperature exceeded the heatsinks' ability to draw the heat off the CPU itself. I would guess that it take anywhere from 30 seconds to a minute for the heat to actually get to the fins, so if your heat sink cannot "sink" the heat all by itself, no fan, for a full minute, then it has inadequate heat transfer and no fan will fix that.
I installed a Corsair H100i and that works very well. I had previously thought that any cooler with less surface area would have less cooling performance, but I have found that if you cannot transfer the heat to the fins, they make no difference. I think a Corsair H60 would have been fine now. I heard that water coolers were "better" and more efficient, but nobody ever explains WHY.
From this experience at least, it appears that water coolers have better heat transfer performance. Fan speeds and fins are secondary to that, as they do not matter until the heat gets to them. If they get hot, then low speed fans can easily remove that heat as higher temperature differentials generally allow for greater heat transfer. If you run high-power and high-heat for a long time, then higher fan speeds help.
How quickly can your test bench ramp up in power? Was that tested? Was that considered? CPU's can hit maximum power in nanoseconds, and crash in milliseconds. Only the base of the HSF would see anything from that event. I think this test is more academic, and not very relevant in the real-world with actual CPU's. It only tests for maximum heat generation over time, like when running benchmarks, not the dynamic nature in which CPU's operate for most useful loads. But then, that's just my perspective.
Pissedoffyouth - Tuesday, July 7, 2015 - link
I agree with you. I think the heat transfer through heatpipes takes quite some time to get to the fins