Noctua NH-L9i Review

The NH-L9i is a horizontally orientated low profile cooler that sits very low and bolts straight onto the motherboard. There are 2 versions available – one for Intel 115x sockets and one for AMD. This makes sense given that the mounts are part of the heat sink itself and it doesn’t use a mounting bracket. By integrating the mounting mechanism to the cooler, Noctua were able to stick to a crazy profile of 37mm tall. The 37mm is made up of a 23mm heat sink and a 14mm thick 92mm diameter PWM fan. The implementation of PWM fan on this cooler means that with the right fan profile, noise levels shouldn’t be a problem provided that you comply with the TDP limitations.

Back in January, we reviewed the Noctua NH-L12 low profile CPU cooler. Since then, we have had the chance to see it’s little brother, the NH-L9i (the “i” being for the Intel version).  In our January review of the L12, we defined CPU HTPC cooling utopia as: 

  • a low profile in terms of height
  • low acoustic properties
  • good cooling capabilities for a CPU at stock volts
  • reasonable price 

Little did we know, this little guy was about to tick all of our boxes.

If the NH-L12 is considered low profile, I’m not sure what to call the NH-L9i – it’s so small that I was seriously concerned for the well-being of my i5-2500K even at stock volts. I know that it was at the L9i’s TDP limit and the case ventilation in the R3 is pretty good but the unit just didn’t look big enough to do the job let alone do it quietly. I know we tend to go on about the packaging of Noctua products in our reviews but the unboxing of the NH-L9i felt a little more ‘Premium’ than usual. For a start, the box was pretty small but it felt heavy. When opening the box, there was a black rubber liner in the top with the thermal paste, mounting screws, case badge and noise adapter.

When I took the black liner out, the size of the cooler really took me by surprise – it really was the size of the cut out. I took all the cardboard out and sure enough, no mounting bracket is required, this one just goes straight on the socket without any mucking around. the mounting instructions were pretty straight forward.

We tested the NH-L12 on an i5-2500K because the only other 115x chip we had in the test lab was an i7-3770K. We saw the warnings on Noctua’s website about overclocking and decided to cautiously test it with our 2500K at stock volts with a fallback plan to turn off the turbo if the NH-L9i struggled. As you will see from our results, this cooler isn’t in the same league as the NH-L12, D14 or H100 and nor should it be, it’s one of the smallest coolers I’ve ever seen. What surprised us was that it effectively cooled our 2500K and did so very quietly.

TDP Guidelines

As per the Noctua website:

  Sandy Bridge  

65W or less



  Recommended with good case ventilation only.

  Ivy Bridge  

65W or less



  Recommended with good case ventilation and Intel Turbo Mode disabled only.


CPU temperatures depend on various different factors, so please take note of the explanations below and keep in mind that our recommendations can only serve as general guidelines for typical setups.

1) Our recommendations are based on an ambient temperature of 25°C or less. If your ambient temperature is significantly higher (30°C or more), we don’t recommend running the NH-L9i on 77W Ivy Bridge or 95W Sandy Bridge CPUs. For all other setups, please ensure good case ventilation when ambient temperature is 30°C or more.

2) Our recommendations assume that the cooler is installed in a typically equipped, properly ventilated HTPC system. If you are using particularly hot components inside your system, it may be necessary to use stronger case ventilation to ensure sufficient CPU cooling performance.

3) Our recommendations assume that the fan is used with PWM control (configured so that it can speed up to 100% when necessary) but without the supplied Low-Noise Adaptor. If you would like to use the NH-L9 with the supplied Low-Noise Adaptors, we recommend choosing CPUs with less than 65W TDP.


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