Our Verdict
The Noctua NH-L9 offers incredible cooling power from such a low-profile heatsink. It's a little noisy when it's running at full pelt, and it's not cheap either, but it can keep a Ryzen 9 CPU in check in a mini PC build where space is tight, and that's a great engineering achievement.
- Very compact design
- Impressive cooling capacity
- Can be very quiet
- Quite pricey
- Loud under full load
- Limited to single CPU manufacturer
The Noctua L9 range of CPU coolers has been a staple of the mini PC cooling market for a couple of years, and recent tweaks to the design, plus the availability of adapter kits, have enabled them to cater to Intel’s LGA1700 socket, as well as AMD’s new Socket AM5 CPUs.
Noctua has a great reputation for the build quality of its air coolers, as well as their low-noise operation and cooling capabilities. The company’s designs are regularly considered to be the best CPU coolers available when it comes to air cooling, and the Noctua L9 series builds outward, rather than upward, so you can squeeze these coolers into tight spaces. That’s ideal if you’re planning to build a gaming PC based on a mini-ITX motherboard.
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Specs
| Socket compatibility | AMD Socket AM5 and AM4 |
| Dimensions with fan (W x D x H) | 114 x 92 x 37mm |
| Weight with fan | 465g |
| Fans | 1 x 92mm Noctua NF-A9x14 PWM |
| Stated noise | 14.8dBA-57.5dBA |
| Extras | Noctua NT-H2 thermal paste, low-noise-power adapter |
You need to buy different versions of Noctua’s L9 depending on the CPU socket found on your motherboard, though. There’s an adapter kit to turn the AMD Socket AM4 version into an AM5 cooler, but the Intel LGA1700 version can’t be used on any other sockets. We’re reviewing the L9a here, where the ‘a’ stands for AMD. The L9i name is used for the coolers for Intel sockets.
Design
The L9a cooler has just two heatpipes attached to a 114 x 92 x 23mm heatsink that spreads out from your CPU socket, while its 15mm-thick, 92mm fan can spin at a peak speed of 2,500rpm. This makes for a total cooler height of 37mm, giving it an exceptionally low profile. That’s ideal if you’re trying to build a powerful mini gaming PC in a case with minimal CPU cooler clearance.
Extremely thin fans can lack the static pressure required to shift enough air through thick heatsinks, but the Noctua benefits from a slightly longer heatsink than rival slim coolers. However, some of this heatsink protrudes beyond the fan, so it isn’t actively cooled.
The L9a secures to a Socket AM5 motherboard using pins that pass through the threaded holes in AMD’s new socket plate, requiring you to remove the plastic clips that are installed as standard. Installation is a bit awkward, though, as the pins pass straight through the socket threads. This means you need to hold the pins and cooler at the same time, which can be fiddly. This cooler also includes a tube of thermal thermal paste that will last for several applications.
Given that it can be quite tricky to install a CPU cooler in the tight space on a mini-ITX motherboard, the ability to reapply thermal paste if you get installation wrong the first time is very welcome. If you’ve not done this before, check out our guide on how to apply thermal paste, where we take you through the process.
In addition to thermal paste, Noctua also includes a low-noise adapter cable, which reduces the fan speed, even in PWM mode. That’s great for keeping the noise down if you have a low-spec CPU, but you’ll want this cooler to be able to ramp up to full speed if it’s sitting on top of a new Ryzen 9 chip.
Performance
As the L9a is only compatible with AMD sockets, we chose a slightly different test to our usual one for CPU coolers, strapping it to a 12-core AMD Ryzen 9 7900 CPU. This 65W 12-core processor offers amazing performance at a super low TDP, making it a prime candidate for the sort of higher-end loads to which this cooler might be subjected.
We record the delta T when testing CPU coolers, where we subtract the ambient room temperature from the CPU temperature reading, which enables us to test in a lab that isn’t temperature-controlled.
We used Cinebench’s ten-minute stress test to dish out the heat, using Ryzen Master to record the temperature. The Noctua cooler was loud at full speed, with a noticeable airflow noise. However, it managed to maintain a CPU delta T of 55°C, which is very impressive, and this test is of course with the CPU under maximum load.
The CPU hit an all-core boost of between 4.3 and 4.4GHz, which was exactly what we saw with our water-cooled test bench with this same CPU. Using the Noctua low-noise adaptor saw the temperature rise by 6°C, but it was still able to offer a full all-core boost frequency with this adapter, which noticeably reduced the amount of noise it made.
Can it go further than this? To find out, I paired the Noctua L9a with a Ryzen 9 7950X. At stock settings, the CPU instantly hit 95°C in Cinebench, with boost frequencies quickly falling below 4.8GHz and ending up closer to 4.6GHz at most by the end of a relatively quick multi-threaded test. Its score of 33,149 was quite a bit lower than we saw in our review too due to the limited cooling, and after a couple of runs this score fell down 30,512 as the CPU continued to throttle.
Applying the 65W Eco mode unsurprisingly saw the score fall to 27,487 – still a match for Intel’s Core i9 12900K and faster than the Ryzen 9 5950X – but the CPU temperature fell to just 75°C under load, with these figures not budging much after several benchmark runs. Despite the slower-than-stock performance, it was great to see a tiny low-profile cooler dealing with a 16-core monster and outperforming the flagship CPUs from the last generation.
The really interesting test came with the 105W power limit, which I set using limits of 142,000 PPT, 110,000 TDC, and 170,000 EDC in the motherboard’s BIOS. Not only did this result in similar boosting frequencies across small numbers of cores, but the CPU was also able to maintain higher all-core boost frequencies and higher scores in Cinebench across all the benchmark runs I completed.
This is the sweet spot, reining in power limits enough to reduce temperatures to a point where the CPU could maintain slightly higher frequencies, but without cutting performance like the 65W mode.
Clearly, I wouldn’t recommend using a Ryzen 9 7950X with a Noctua L9a cooler in any situation other than extreme circumstances. After all, Noctua itself says the cooler and CPU are incompatible due to the modest cooling on offer, but this shows the potential power of the L9a, as well as the benefits of tweaking your AMD CPU.
Price
The Noctua L9 price is $45 with a silver heatsink and brown fan, but you can also spend an extra $10 to get the more aesthetically pleasing black version (pictured above, with the screws for the optional ducting kit), which costs $55. These prices aren’t overly expensive for a decent CPU cooler, Noctua makes air coolers that cost double this amount, but it’s not outstanding value considering this cooler’s modest size and restriction to only specific motherboard sockets (depending on the version you buy).
Verdict
The Noctua L9a certainly has its limitations, such as costing more for a nicer-looking black version and being limited to using either Intel or AMD CPUs, depending on which version you buy. It can also get a little loud under full load.
However, its cooling performance is surprisingly powerful for such a low-profile cooler, allowing you to cool some of the best gaming CPUs in a small, tightly-packed mini PC case, while generally staying quiet. If you want to build the best mini gaming PC possible, in a small mini-ITX case where there’s no room for an AIO cooler, and still use a powerful CPU, then this is a great low-profile CPU cooler.