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Noctua NH-L9a-AM4 CPU Cooler Review

Manufacturer: Noctua

Cooler Features, Design, and Included Accessories

Features

Courtesy of Noctua

  • New revision for Ryzen’s AM4 socket
  • 37mm low profile
  • 100% RAM compatibility
  • 100% compatibility with PCIe cards on mini-ITX
  • Easy access to near-socket connectors
  • NF-A9x14 PWM premium fan
  • Low-Noise Adaptor
  • Custom-designed SecuFirm2™ mounting for AM4
  • NT-H1 thermal compound
  • 6-year manufacturer’s warranty

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The Noctua NH-L9a-AM4 CPU cooler is a low profile unit designed with performance and compatibility in mind. The cooler comes stock with a single 92mm fan, nickel-plated copper heat pipes and base plate, and a horizontal radiator sitting between the fan and the baseplate. The unit's two integrated heat pipes are constructed out of copper to optimize heat absorption from the CPU base plate and heat transfer to the aluminum radiator. The aluminum radiator was designed to facilitate optimal transfer of the heat from the heat-pipes to the air medium. The thin nickel plating encasing the base plate and heat-pipes give them corrosion and scratch resistance, while not inhibiting heat transfer between the cooler's components.

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The unit's fan sits directly on top of the radiator, oriented to blow air through the radiator towards the board's surface. This airflow pattern has a secondary benefit since the airflow with act to cool components surrounding the CPU socket (like the VRMs, VRM heat sinks, and system memory). The fan is fixed to the radiator via four screws that mount to a shroud framing the radiator.

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The NH-L9a-AM4's radiator was designed with a fin density of 16 fpi (fins per inch) with the radiator being about the thickness of a standard 120mm system fan. The radiator's thickness does not work against the fan airflow, but a fan with a greater amount of static pressure is required to overcome the "backwash" effect caused by the airflow rebounding from the motherboard's surface. The two integrated heat pipes are U-shaped to maximize heat dispersal throughout the radiator. The heat pipes are pressed into the upper surface of the CPU base plate, and redirect the heat along their U-shape to the outer edges of the radiators. To aid in heat transfer to the radiator fins and add rigidity to the structure, the heat-pipes are individually soldered to each of the aluminum radiator fins.

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From the side view, You get a better look at the unit's construction and the radiator's thickness (given that the included 92mm fan is a mere 12mm thick). Along the middle of both sides of each radiator is a fold-down spacer to give the fins rigidity, as well as to act as an air guide.

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The unit's base plate is a seamless copper plate with nickel-plating to prevent corrosion and surface scratches. The base plate is fixed to an upper plate to which the hold down assembly is fixed, sandwiching the copper heat pipes. The heat pipes run through the center portion of the base plate to ensure optimal heat transfer. The base plate is machined flat and polished to a mirror-like sheen, ensuring a near-perfect mating surface with the CPU. Notice that the mounting bracket are fixed directly to the outer edges of the base plate with mount points on the brackets containing threaded holes for the mounting screws. This means that the cooler mount posts go through the board from the bottom up, instead of the normal top down method. While this allows for a much more compact design, it makes for a much more challenging heat sink install. We found that it was nearly impossible to install the cooler unless the board was physically removed from its enclosure, and required two hands (and some patience) to complete.

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There are absolutely no fit issues with the NH-L9a-AM4 mounted to the test bench's AM4-based board. All DIMM slots remain easily accessible and the radiator's minimal dimensions keep it well away from the surrounding VRMs and heat sinks. Further, the radiator is lifted enough from the surface of the board to clear any close-in capacitors.

Included Accessories

Noctua includes all necessary mounting hardware and accessories needed to setup and install the NH-L9a-AM4 into your system, including fans, motherboard and fan mounting hardware, and thermal compound.

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For cooler to board mounting, Noctua includes a detailed instruction sheet for use with the AMD AM4-type sockets. The also include a metal case badge to show off your cooler preference with pride.

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The cooler comes preassembled for the most part, so a minimal amount of accessories are needed. Noctua includes a custom back plate, mounting screws , fan screws for mounting a 25mm thick fan to the unit, a low noise adapter to reduce fan speed, and their NT-H1 thermal paste with enough provided for several system installs. The mount screws fit through the provided base plate to screw into the mounting brackets in the cooler base.

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The mounting bracket is one of the simplest that I've seen from Noctua, consisting of threaded posts that go through the base plate, screwing into the backets on the underside of the unit's base plate. In practice, this simple design is much harder to use than anticipated, requiring board removal from the system and two hands to hold the cooler and base plate in place while attempting to screw in the mounting posts.

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For NH-L9a-AM4, Noctua packaged in one of their NF-A9x14 92mm fans. The NF-A9x14 fan is rated for a maximum speed of 2500 RPM with a rated maximum airflow potential of 33.8 CFM (cubic feet per minute). The brown colored fan body sits in a tan colored housing with a total of nine large fan blades. The fan blades have shaped fins along the inside top of the blade to assist in directing airflow into the radiator and minimize the airflow dead spot in the fan's center caused by the motor. The fan cables are sleeved in a dense, black colored plastic sleeving and ending in a 4-pin PWM-style power connector. The fans is rated to run at 12V, drawing 0.21 amps of power during full speed operation.

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March 29, 2018 | 03:43 AM - Posted by djotter

Hi Morry, thanks for the great write up. Do you have any experience with any of the Wraith coolers? Just wondering how this compares for performance and noise.
I have a 2400G for my HTPC and the wraith stealth cooler makes too much noise, I have it turned down to 15% fan speed to make it quiet enough.

March 29, 2018 | 09:33 AM - Posted by Morry Teitelman

Have not had any experience with the wraith cooler unfortunately.  This one is much quieter than most other coolers I've tested.  As far as the noise output reported by vendors, the numbers themselves may be acurrate, but how they measure them (ie, equipment used and distance to source) probably varies greatly.  That would even be true between sites.  For example, I use an audio app on my cell phone to measure from a 3ft distance.  For all of my reviews, the sound measurements would be consistant and comparable, but probably not between my reviews and those of Sebastian (b/c he uses different gear for measurement).

In any case, this cooler, or any Noctua cooler for that matter, will be much quieter than the wraith cooler.

March 31, 2018 | 10:21 PM - Posted by Photonboy

How much would a typical CASE raise the temperature?

It seems the testing was done without a case?

Assuming 25degC average that means the CPU would be roughly 68degC under load... while that leaves about 12degC (80degC is max recommended for sustained usage I believe) I suspect you would be hitting 80degC in a small case with so-so air flow.

That's fine still for both cooling and noise (22dB is silent) though overclocking may not be feasible due to temp in some situations.

April 1, 2018 | 02:23 PM - Posted by Morry Teitelman

If you are looking to overclock, I would not recommend using this cooler.  As far as your initial question goes, it really depends on case airflow.  Assuming you have decent front to back airflow (ie, fans mounted in front grill and in rear panel), you should see temps on par or may 5C higher.  However, the "stress" temps reported are under extreme use scenarios.  I wsa using the stress tool in AIDA64, which puts the CPU under 100% load across all cores.  During normal gaming and use sitruations, you would not see anywhere near that load...

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