We had our concerns that the NH-D15 simply wouldn't live up to its hefty price tag - after all, many of the top-end all-in-one liquid coolers cost about the same. Thankfully, it managed some pretty shocking numbers. In dual fan mode it matched Corsair's Hydro H105 and the Phanteks PH-TC14PE in our LGA1155 test system with a delta T of 38°C, and this only rose 1°C when we removed the front fan too. In fact, even using both fans connected using the low noise adaptors resulted in a delta T of just 40°C, which is the same as Corsair's Hydro H75 and slightly better than Antec's Kühler H20 950 on its extreme profile. Needless to say the latter was a huge amount noisier too.
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Our LGA2011 system proved to be the real sweet spot, though, with only Corsair's H105 managing a better result. Here Noctua's flagship bettered every other air cooler by at least 2°C, which is quite a feat, and it left many dual and single fan all-in-one liquid coolers in its dust too. There was a bigger impact here using the low noise adaptors, which is understandable given the extra heat it's contending with, where the single fan result rose 5°C from 43°C to 48°C. However, this was still a match for many of the liquid coolers on their respective quiet profiles.
Noise-wise, things are certainly audible with the fans at full speed, however it's actually a noise that most will be able to put up with. There's no whining or high-pitched hair dryer-type screaming that we're used to with many of the liquid coolers and the NH-D15 is all but inaudible when using the low noise adaptors. Despite the low noise, though, in our LGA1155 system especially, it remained competitive.
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The NH-D15 might seem expensive, but for LGA2011 owners especially, it performs as well as all the top-end all-in-one liquid coolers out there so in cooling terms it justifies its price. Even on LGA1155, which is easier to tame, it's still extremely potent, matching the 4th best result on test. Perhaps the biggest plus point for those looking to get rid of a small, whiny cooler in time for warmer summer months, the NH-D15 is also very quiet, especially so when used with the included low noise adaptors.
We really can't fault it, other than maybe it's bulky size, but even then its only 165mm high and has options as far as RAM compatibility goes. It's also remarkably easy to install for such a big cooler. So, despite a lofty price tag, this is one awesome cooler that both performs admirably and won't make your ears bleed - far from it. With Noctua's awesome packaging and build quality on hand too, we have no qualms giving top marks.