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Noctua NH-L9a review

Despite its low-profile design, the Noctua L9A CPU cooler offers excellent performance and is able to tame even the likes of the 12-core AMD Ryzen 7 7900.

Noctua L9A CPU cooler black

Our Verdict


Incredible cooling from such a tiny heatsink, although it’s a little louder than the competition too

The Noctua L9 CPU coolers have been a staple of the compact low-profile cooling market for a couple of years, with recent tweaks to the design and availability of adapter kits allowing them to cater not just for Socket AM4 and LGA1700 sockets, but Socket AM5 too.

You need to buy different versions of Noctua’s L9 depending on the CPU socket your motherboard has, though. In addition, you’ll need to factor in the wait time for a Socket AM5 adaptor kit and its LGA1700-compatible version can’t be adapted to other sockets either. Price-wise, the L9a, with the ‘a’ indicating Socket AM4 compatibility, can be had for $45, but if you want the more aesthetically pleasing black version, you’ll need to spend an extra $10.

The L9a cooler has just two heatpipes while its 15mm thick, 92mm fan can heat a peak of 2,500rpm. This makes for a total cooler height of 37mm, which is exceptionally low.

Extremely thin fans can lack static pressure required to shift enough air through thick heatsinks but the Noctua benefits from a slightly longer heatsink than rival slim coolers, though it sits outside of the fan so isn’t actively cooled. Noctua L9A CPU cooler black

The L9a secures to Socket AM5 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 so you need to hold the pins and cooler at the same time, which can be fiddly. The Noctua cooler includes a tube of thermal interface material (TIM) that will last for several applications.

Given how tricky installing such coolers can be in tight spaces on mini-ITX motherboards, the ability to reapply TIM if you get installation wrong the first time is very welcome.

In addition to thermal paste, Noctua also includes a low-noise adaptor cable, which reduces the fan speed even in PWM mode, although we’d argue most people would want to allow a tiny cooler to ramp up to full speed when needed.

Noctua L9a performance

As the L9a is only compatible with AMD sockets, we chose a slightly different test to usual, strapping it to an AMD Ryzen 9 7900. 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 a cooler like this might be subjected to.

Noctua L9A CPU cooler black

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 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, which was still able to offer full all-core boost frequency while noticeably reducing noise.

Noctua L9a review pros and cons


  • Very compact design
  • Impressive cooling capacity
  • Can be very quiet


  • Quite pricey
  • Can be loud under full load
  • Limited to single CPU manufacturer

Noctua L9a specs

AMD Compatibility Socket AM4, Socket AM5
Dimensions with fan (mm) 92 x 92 x 45 (W x D x H)
Fans 1 x 92mm
Stated noise 10dBA-37dBA

Noctua L9a price

With a price of nearly $50, the L9a is not overly expensive for a CPU cooler but considering its modest size and restriction to only AMD CPUs (or only Intel CPUs with the non-a version), it’s not outstanding value.

Price: Expect to pay $44 USD (£44 GBP).

Noctua L9a review conclusion

The Noctua L9a certainly has its limitations, such as costing more for a nicer-looking black version and being limited to 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 good, allowing you to cool several of the latest high-end CPUs, while generally staying quiet.