The novel color scheme resides solely on the fans, which are specifically designed for the task of pushing air efficiently through the narrow gaps between fins of a radiator. Noctua uses nine large, tightly packed blades that cut the air at a low angle to maximize the pressure. A separate family of more propeller-like fans is tailored for use on enclosure walls or with coolers that have wider fin spacings.
There are two different fan designs found on the trio of coolers that has been making the rounds on my test rack: the 120-mm NF-P12 and its P14 brother, which measures 140 mm across. Both models rely on the same core set of technologies.
Let's start with the most obvious attribute: the pair of notches cut into the trailing edge of each fan blade. Noctua calls these vortex-control notches, and they're meant to reduce turbulence, resulting in quieter, more efficient operation. The notches are staggered slightly from blade to blade to spread any noise they create across a wider spectrum to blend in more easily with background noise.
The DC motor charged with generating the actual airflow is a custom Noctua design. According to the company, the motor offers smoother transitions between its coils than lesser motors—another win for silence and efficiency. Noticing a trend here?
The oil-pressure bearing has also received some special attention in the form of a magnet that helps to stabilize the rotating axis and to prevent any abrasion during initial spin-up. Keeping the spindle pristine improves long-term stability, Noctua says, and it backs up the talk with an impressive 150,000 MTBF rating for the fans and a six-year warranty.
We'll test noise levels in a moment, but before that, I should point out one disappointing characteristic of these spinners: they use three-pin DC headers that are incompatible with the temperature-based fan speed switching on some motherboards. Noctua was unhappy with the subtle switching noise it detected on the speed-control ICs associated with four-pin PWM fans, so it set about designing a quieter one for the Focused Flow fan we saw out on display at Computex. Unfortunately, that fan hasn't hit the market yet.
The Focused Flow has integrated rubber bumpers, but Noctua relies on separate strips to dampen vibration noise with its current coolers. On the NH-D14 and C14, a slick clip mechanism is anchored to the fans with rubber stoppers that poke through the screw holes. The clips hold the fans securely to the heatsinks and are easy to fasten and remove, which is a definite improvement over the simpler design found on the NH-U12P SE2 and more than a few of the other air towers I've used over the years:
A bracket for all sockets
I led by talking about Noctua's socket upgrade policy, so forgive me for taking this long to talk about the actual retention bracket that makes this possible. Out of the box, the bracket is compatible with all desktop sockets from AMD since Socket AM2 and from Intel since LGA775. The design is a simple one: two screws anchor the CPU block to posts that poke out of retention bars one screws into the motherboard.
On AMD sockets, the bars screw directly into the existing backplate. Spacers raise the bars to the correct height, and all one has to do is make sure they're oriented in the right direction. Alas, this setup doesn't provide the option of rotating a cooler's orientation by 90 degrees to avoid specific clearance conflicts.
There are no such problems with the Intel retention kit, which has the luxury of slipping into holes arranged in a perfect square. The problem is, that square comes in three different sizes and with different back plates, so a more elaborate bracket is required. Noctua supplies a rubber-lined backplate with a pull-away section for sockets newer than LGA775. There are three distinct notches cut into each of the backplate's arms to match different hole spacings, plus posts, spacers, and a set of thumbnuts to secure the retention bars to the mobo.
Don't have a screwdriver? Noctua provides a rather lengthy one with each of its coolers. The long reach and thin profile is necessary to get at the retention screws on the block, which are inaccessible on all but the NH-C14 without removing at least one fan. On the C14, you can thread the screwdriver between the fan blades and the gaps built into the radiator itself.
Using these coolers primarily in my lab, where systems are pulled apart and reassembled on different motherboards sometimes several times in one day, I quickly found myself frustrated with the retention mechanism. Everything fits together nicely, and the screw threads tolerate multiple installations without losing their grip, but there's a lot of pulling fans and fiddling with the screwdriver.
Most coolers of this size require some disassembly before they can be removed, so the Noctuas are hardly unique in this aspect—the retention system is just less than ideal for quick swaps. For the typical user, who will assemble his system once and then go months if not years before touching it again, the retention bracket will work just fine. Just keep in mind that you'll need access to the underside of the CPU socket in order to add the backplate to Intel systems.
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