Test procedures
We extended our database of processor coolers with the notorious NH-D15. It will serve as a key reference point for every upcoming test because it represents some kind of a standard for air coolers. In this review, we analyzed the functional features of the most popular product in its category. How does Noctua do it?
Basic parameters
| Parameters | Noctua NH-D15 | |
| Compatible sockets | AMD AM3(+), AM2(+), FMx(+), Intel LGA 115x, 2066, 2011-x | |
| Measurements (H/L/W) fan included | 165 × 161 × 150 mm | |
| Weight of the heatsink, fan included | 972/1312 g | |
| Number and thickness of heatpipes | 6× 6 mm | |
| Thickness (and gaps) of ribs | Ventilátor | 0,4 (1.85) mm |
| From the middle of the base to the edge of the fan (and heatsink)* | 95 (73) mm | |
| Possibly conflicting RAM slots and collision height** | 2 – 4 (34 mm) | |
| Fan | 2× 140 mm | |
| Starting RPM (and voltage) | Minimálne štartovacie | 667 (4.82 V) |
| Max. RPM | Maximálne (12 V) | 1494 |
| Bearings | SSO2 | |
| Approximate price | 85 eur |
*These measures indicate distances between the cooler and RAM slots, or more precisely the nearest PCIe × 16 slot.
**The data reflect the situation on Mini-ITX boards which typically have 50 mm from the center of the socket to the first slot. With the ATX format, it can be up to 7 mm more and that means one extra slot and a wider compatibility than is mentioned in the table. We measured the height limit with fans that are aligned with the maximum specified coolers height.
Details
The heatsink weights almost a kilo and there are not many bigger pieces out there. Its design is excellent. It is solid, it has a nickel-plated finish, and everything is done with precision. All parts fit perfectly together and are finished to the last detail, including edges and brazing. Between the ribs and pipes, the rigid connection is clearly visible round the whole surface, but without any defects. The tracks are perfectly covered also on the base.
The contact area of the base is slightly convex (for a better contact with the IHS) and its structure has small grooves. They provide a better symbiosis with compounds that have higher viscosity. Compared to smooth surfaces, air bubbles are not a problem here. Sure, under the ideal conditions, mirror-polished surfaces are more efficient.
Two NF-A15 fans with various improvements are included. There are really many of those improvements and we do not want to bore you with theorizing about each one of them (we will test them in practice someday, it will be more interesting …). Transferring fan vibrations to the radiator is eliminated by soft rubber pads. And on each of the blades there is a trio of small projections. Their task is to direct the airflow to places where the triangular cuts on the edges of the ribs reduce the resistance of the flowing air. This should maximize the intensity of airflow around places with the most significant heat exchange while maintaining the lowest noise level possible.
Really important are bearings with the magnetic stabilization of the rotor axis. Time has already shown that they are extremely durable and even after years they retain their original properties without producing disturbing sounds. The fan is optimized for PWM operation, and after manual tuning of the curve it can achieve stable 180 rpm. With fixed voltage control, it starts at 667 rpm. This can make more demanding users a bit unsatisfied because the process is louder than very quiet.
The rotor is quite heavy and to make it start moving you need at least 4.8 V. When it is running, however, even 4.35 V is enough to maintain a lower speed (450 rpm with a tolerance of +/- 50). But with such a setting, the speed is overly volatile and the fan obviously suffers.
With dual tower coolers, RAM compatibility is almost always compromised. The only exception in the case of D15 is with Mini-ITX boards, where both DIMM slots fit nicely to a cutout in ribs. It is up to 7 cm high, which exceeds any commonly available module. ATX boards are a bit bigger problem. The slots on them are more shifted from the socket, and the second (and every other) slot can also collide.
At least you can use all slots for 32-millimeter modules with the specified heatsink height (165 mm). To use higher modules, you can, of course, attach the fan a bit higher, but that can mean a collision with a side of your case.
It is tight everywhere, even near the graphics card. The first slot on our motherboard (Gigabyte X99-UD4) was blocked. However, it is relatively close to the center of the socket –75 mm. It is two centimetres more on most of other boards. But even so, the access to the lock of the slot can be very difficult. The complicated (dis)assembly of graphics cards is resolved by D15S which has the base out of the axis of the first PCIe (the ribbing is further away). But this package includes only one fan.
We extended our database of processor coolers with the notorious NH-D15. It will serve as a key reference point for every upcoming test because it represents some kind of a standard for air coolers. In this review, we analyzed the functional features of the most popular product in its category. How does Noctua do it?
Test procedures
Tests begin with the analysis of fans. Using the Gophert CPS-3205 II laboratory power supply and the UNI-T UT372 laser tachometer, we detected the initial speed. That means determining the minimum voltage required to move the rotor in the idle stage. Subsequently, we regulated the revolutions by hundreds (from 400 rpm to the round maximum), which gave us the first part of the data to create a curve that indicates the noise increase according to rpm. To make the results as accurate as possible we took the average values of 30 seconds long sequences and regulated the fans by the hundredths of volt until the tachometer reached a specific value, for example 800 rpm. Finally, we noted down the maximum rpm and put values into the parameters table.
To assign a specific noise level to a specific speed, we put the coolers with corresponding voltages to the soundproof box in which we measured the noise. This was done using the Reed R8080 sound level meter that was recalibrated before each set of measurements. The positions of the polyethylene pad on which the coolers were fixed, and the sound level meter were always the same. To achieve the most precise logging even with the lowest flow the distance between the sensor of the meter and the fan was approximately 25 cm. Each measurement was performed in real time. The meter sent 30 sound samples to the computer, from which we took the average value and put it into the charts. The most important part was to find and to align the fan settings to fixed noise levels. In this case, 45, 42, 39, 36, 33, and 31 dBA were selected, and with the exception of the last and the penultimate mode, each further decrease of rpm reduced the noise level by a half. On the one side there was noisy 45 dBA and on the other almost completely silent 31 dBA.
If one of the modes is missing in the charts, it is either due to insufficient cooling performance or because it was not possible to regulate the fan to the desired noise level. Each test lasted 600 seconds. We simulated the burn in IntelBurnTest (7500 MB) and the result represents the average of maximum temperatures of CPU cores, which were captured in Core Temp. At the time when some of the cores reached 95 °C, the tests were interrupted and considered unsuccessful.
Cooling performance tests were done in our plexiglass wind tunnel with a motherboard in the vertical position, just like in a usual tower case. The scheme of the system cooling was traditional, balanced flow was provided by four Noctua NF-A12S PWM fans. Two were at the input and two at the output, regulated to 550 rpm.
The intake air temperature was 21 – 21.3 °C, ensured in our air-conditioned lab so we could also accurately measure the automatic regulation PWM. Only during this process we put the processor with TDP 140 W back to the factory settings. The curve of the profile of the impulse modulation was set, regarding to low noise level, to 20 % ≤ 20 °C – 30 % ≤ 40 °C – 40 % ≤ 60 °C – 100 % ≤ 90 °C.
| Test configuration* | |
| Processor | Intel Core i7-5930K@4,2 GHz (1,15 V) |
| Thermal compound | Arctic MX-2 |
| RAM | G.Skill Flare X, 4× 8 GB, 3200 MHz/CL14 |
| Motherboard | Gigabyte GB-X99-UD4 (BIOS F23) |
| Graphics card | MSI GeForce GTX 1060 Gaming X (6 GB) |
| SSD | OCZ RevoDrive 400 |
| Power supply | SeaSonic Prime 650 W (80Plus Titanium) |
*Without overclocking, the power consumption of the configuration during IntelBurnTest load was around 170 W; 225 W with overclocking (approximately 180 watts by processor).
We extended our database of processor coolers with the notorious NH-D15. It will serve as a key reference point for every upcoming test because it represents some kind of a standard for air coolers. In this review, we analyzed the functional features of the most popular product in its category. How does Noctua do it?
Automatic regulation
| Cooler | Fan speed | |
| Burn | Idle | |
| Arctic Freezer 33 | 1× 1119 rpm | 0 rpm |
| SilentiumPC Fera 3 v2 | 1× 746 rpm | 1× 619 rpm |
| Noctua NH-D15 | 2× 627 rpm | 2× 468 rpm |
We extended our database of processor coolers with the notorious NH-D15. It will serve as a key reference point for every upcoming test because it represents some kind of a standard for air coolers. In this review, we analyzed the functional features of the most popular product in its category. How does Noctua do it?
Max. RPM
| Cooler | Fan speed | |
| Arctic Freezer 33 | 1× 1350 rpm | |
| SilentiumPC Fera 3 v2 | 1× rpm | |
| Noctua NH-D15 | 2× 1494 rpm |
We extended our database of processor coolers with the notorious NH-D15. It will serve as a key reference point for every upcoming test because it represents some kind of a standard for air coolers. In this review, we analyzed the functional features of the most popular product in its category. How does Noctua do it?
45 and 42 dBA
| Fan speed | Speed and voltage of fans | ||||
| 45 dBA | 31 dBA | 42 dBA | 31 dBA | ||
| Arctic Freezer 33 | Arctic Freezer 33 | – | – | 1× 1272 rpm | 10.65 V |
| SilentiumPC Fera 3 v2 | SilentiumPC Fera 3 v2 | – | – | 1× 1550 rpm | 10.9 V |
| Noctua NH-D15 | 2× 1330 rpm | 10.45 V | 2× 1200 rpm | 9.24 V |
We extended our database of processor coolers with the notorious NH-D15. It will serve as a key reference point for every upcoming test because it represents some kind of a standard for air coolers. In this review, we analyzed the functional features of the most popular product in its category. How does Noctua do it?
39 and 36 dBA
| Cooler | Speed and voltage of fans | ||||
| 39 dBA | 31 dBA | 36 dBA | 31 dBA | ||
| Arctic Freezer 33 | Arctic Freezer 33 | 1× 1157 rpm | 9.1 V | 1× 1041 rpm | 7.78 V |
| SilentiumPC Fera 3 v2 | SilentiumPC Fera 3 v2 | 1× 1409 rpm | 9.52 V | 1× 1229 rpm | 8.25 V |
| Noctua NH-D15 | 2× 1073 rpm | 8.1 V | 2× 933 rpm | 6.77 V |
We extended our database of processor coolers with the notorious NH-D15. It will serve as a key reference point for every upcoming test because it represents some kind of a standard for air coolers. In this review, we analyzed the functional features of the most popular product in its category. How does Noctua do it?
33 and 31 dBA
| Cooler | Speed and voltage of fans | ||||
| 33 dBA | 31 dBA | 31 dBA | 31 dBA | ||
| Arctic Freezer 33 | Arctic Freezer 33 | 1× 900 rpm | 6.51 V | 1× 733 rpm | 5.28 V |
| SilentiumPC Fera 3 v2 | SilentiumPC Fera 3 v2 | 1× 1000 rpm | 6.79 V | 1× 828 rpm | 5.7 V |
| Noctua NH-D15 | 2× 700 rpm | 5.87 V | – | – |
We extended our database of processor coolers with the notorious NH-D15. It will serve as a key reference point for every upcoming test because it represents some kind of a standard for air coolers. In this review, we analyzed the functional features of the most popular product in its category. How does Noctua do it?
Conclusion
NH-D15 probably still remains (even after three and a half years after the release) the most efficient commercially available CPU cooler. That sounds like a courageous claim, but it is based on my previous work – the great comparison of CPU coolers on ExtraHardware.cz. There were practically all competitors who had the ambition to endanger the position of Noctua, including Raijintek Thisis, and Cryorig R1 Ultimate.
The cooling performance is very high even at low noise levels. And even though the fans can go really wild, the cooler is optimized for exceptionally quiet operation. This is supported by the fact that the temperature variation between the maximum noise level (48 dBA) and really silent 33 dBA is only about 4 degrees Celsius (180 W). The cooling performance decreases linearly as well as the noise level, according to the speed/airflow. Compared with cheaper coolers (for example, SilentiumPC Fera 3), it is clear that D15 is dominant with a lower airflow rate because the big heatsink makes a difference. However, the price for it are various possible collisions.
It is quite complicated to talk about what you get for the money. You get extra details and precise work. Only BeQuiet! can compete when it comes to fans (we are still talking about the same price category), but, for example, Dark Rock Pro 3 is known for its really complicated and difficult assembly. Noctua represents the opposite, SecuFirm is the top-notch mounting system that has been copied many times, but Noctua leads right from the start.
However, despite the fact that NH-D15 is very reasonable choice, it is not a prototype of a perfect cooler. There are some drawbacks. But that is beyond these standard tests. We will give that a closer look in the upcoming bonus review.
| Noctua NH-D15 |
| + excellent cooling performance |
| + balanced performance over the entire speed spectrum |
| + performance does not decrease even after reducing the speed |
| + very quiet PWM, both in idle and in burn |
| + handy assembly |
| + you can use heatsinks for RAM in the first two slots (up to 7 cm) |
| + excellently made heatsink |
| + top-notch fans with a long lifespan |
| + great ssupport from the manufacturer, a possibility of compatibility for several years |
| - collision with higher memory modules (over 34 mm) and, sometimes, with the first PCIe × 16 slot |
| - you can turn the heatsink only in one direction when using AMD CPU |
| - the price |
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