Noctua NH-L9a-AM4 Review (Page 2 of 4)

Page 2 - Physical Look - Hardware; Installation

It has been a while since I have reviewed such a small cooler, and the Noctua NH-L9a-AM4 is exactly that. Much like other L-series, we have a single stack of horizontal fins and some heatpipes going through it. In this case, we have two heatpipes that come out of the bottom base and down the sides of the fins. As the branding makes its reappearance once again, we have a full matte black finish on the heatsink and the fan. It really is a clean look that I am super pleased to see from Noctua. The heatsink is still made out of aluminum and nickel plated around the entire unit. Noctua's owl logo can be found on each side of the heatsink, but is mostly hidden with how short this cooler is.

The fan attached to the Noctua NH-L9a-AM4 is a 92mm NF-A9x14 HS-PWM, attached to the heatsink with four screws. The fan itself has rubber pads in each corner, which should reduce any noise and vibrations. As we have mentioned, the fan is 14mm thick and weighs 75g. This is still a light and mini fan overall. It rotates at speeds of up to 2500RPM, with an airflow rating of 57.5 cubic meter/hour, static pressure of 2.11 mmH2O, and a noise level of 23.6 dbA. Noctua also has mentioned we have a SSO2 bearing inside, which is a hydrodynamic bearing for quieter operation and longer life. This results in a mean time to failure of over 150,000 hours, or just over seventeen years.

In terms of weight, the whole Noctua NH-L9a-AM4 weighs 390g without a fan and 465g with the fan installed. This is still a very compact cooler, but the weight makes it feel also quite dense. For some perspective, a typical Intel stock cooler weighs around 330g, while an AMD Wraith Prism stock cooler weighs 582g. Most of the weight can be attributed to the material choices of the heatsink itself, as you will also find out later.

From the side, you can see all of the fins are stacked in a rectangular shape. There are several indents on both sides of the metal fin edges. This optimizes the ability to permit airflow in between the fins while reducing the resistance and noise, all while only negligibly decreasing the heatsink surface area. There is a total of 67 fins on the radiator. The spacing in between each fin is approximately 1.5mm. From my calculation, the total surface area of the cooling fins combined is close to 0.21 square meters. Comparatively speaking, the CRYORIG C7 has a slightly higher 0.27 square meters of surface area.

In terms of dimensions, you can see the heatsink is about 23mm in height, 114mm in width, and 92mm in depth. With the fan attached, the height increases to 37mm, which is much lower than other coolers we have taken a look at in the past. This CPU cooler is small enough so there is no part hanging over into other areas on the motherboard like the motherboard or the first PCI Express slot underneath. As such, Noctua mentions this cooler has full compatibility with the modern AMD AM4 socket without any interference with memory. These dimensions should suggest to users and reviewers that this cooler is fully meant to be used for smaller builds and in tighter quarters like a home theater PC.

Out of the base of the Noctua NH-L9a-AM4 are two heatpipes, splitting to each side. The bend out and go back through the array of fins on each side. While it is not exactly a symmetrical design, you should be able to mount the NH-L9a-AM4 in either of the two orientations without worrying of affecting cooling performance. The heatpipes are around 6mm in diameter, and like the base, is a copper core with a nickel plating on the outside. Heatpipes are supposed to efficiently lead the heat away from its source due to the low heat of vaporization, or phase change energy, of alcohol. The heatpipes are aligned in a manner to spread out the heat in the single array of radiating fins. These pipes along with the fins and the fan attached should be able to dissipate heat quite well, but we will see if this is true in our performance tests.

From the photo above, you can see the bottom of the Noctua NH-L9a-AM4 CPU heatsink. As you can see, the base is very flat, which means practically the entire base should rest evenly on the processor. After a quick inspection, I was not able to see any abnormalities, though you can see the circular milling marks. As such, it is important that you use some sort of thermal grease between the base and your processor to fill in these smaller gaps. As you can tell, the finish is everywhere around the heatsink besides the base, which is understandable. As we have seen from past Noctua heatsinks, this heatsink is composed of copper, nickel, and aluminum. The base and heatpipes are built using copper for best heat transfer ability with a thermal conductivity of 401 W/mK. The heatsink fins utilize aluminum as it is quite a bit lighter in comparison to copper. This compromise allows the NH-L9a-AM4 to reduce its weight and thus reducing the stress on the motherboard. Aluminum has a thermal conductivity of 237 W/mK, which is not as optimal for heat transfer, but the trade-off is understandable.

Visually speaking, the Noctua NH-L9a-AM4 conceals the copper color with its heatpipes and base. The electroplating of the base with nickel on top of copper has a thermal conductivity of only 90.9 W/mK. While nickel has a lower thermal conductivity than copper, the electroplated layer is very thin and should not directly affect performance to a significant degree. Instead, this is done this way to keep the base from corrosion. Nickel and nickel-base alloys generally have desirable properties that can withstand corrosive environments and high temperatures, which are especially beneficial for a heat dissipation device. The reason why nickel has such a property is because of nickel's ductility and toughness all the way up to the melting point of 1455c, measured at non-standard pressure. Nickel's face-centered cube crystal structure is virtually unaltered all the way up to that temperature. Nickel, like titanium, is highly resistant to corrosion so corroded material will not build up on the surface in the long run. As a result, the Noctua NH-L9a-AM4 will be less prone to losing its cooling performance over time as juxtaposed to a corroded copper surface.

Additionally, all the joints are cleanly soldered at the base while the heatpipes are soldered to the fins. Pressed fins are typical for most heatsinks, but this can lead to degradation over time as contact between metals decreases due to thermal expansion and contraption. Overall, the Noctua NH-L9a-AM4 appears to be built very solidly. Reliability should also be excellent and Noctua offers a six-year warranty should anything go wrong.

As you have read in our other Noctua reviews, installation is pretty straightforward. However, this compact cooler uses a different system compared to the traditional mounting setup, despite having the same SecuFirm2 name. As I have mentioned and can tell by the name, this is only meant to be installed on the AMD AM4 socket, so the backplate it comes with are meant only for the mounting holes on this socket. The backplate it comes with is marked NM-ABP4.

Once the backplate is in place, I would be sure to place thermal paste between the processor and the heatsink. On an AMD processor, like the recent Ryzen CPUs, Noctua advises to put a small dot measuring in 4 to 5mm in diameter with a square pattern of four dots surrounding the middle one. Next, place the cooler in place on the motherboard side and flip over the motherboard to start screwing in the included screws from the backside. The screws are black in color, but also have plastic spacers. With your screwdriver, I would make sure you tighten the screws in an alternating cross pattern to ensure each corner is firmly attached to the motherboard. Overall, installation was quite clear, but I would not necessarily say it was easy, especially since you have to screw the heatsink from the back while holding it in place. This would have been much easier in a smaller form factor size, since you would have easier access to both sides of the motherboard at the same time. The alternative would be to fully uninstall the motherboard from the case. As I have noted before, the NH-L9a-AM4 does not interfere with my RAM, as the cooler has a very small footprint. With the physical inspection, we can see Noctua is consistent in both its build quality and aesthetics as it has been with past products.

Page Index
1. Introduction, Packaging, Specifications
2. Physical Look - Hardware; Installation
3. Test Results
4. Conclusion