Mini-ITX systems have become more attractive over the years for a number of reasons. The selection of boards and cases has improved dramatically, for example. Processor TDPs have fallen, as well, making it easier to cool the chips in small enclosures with relatively little airflow. Finding a quiet CPU cooler that fits inside a tiny Mini-ITX chassis can be difficult, though. Stock heatsinks are a little on the noisy side, and so are the low-profile models meant for servers.
At the Computex trade show earlier this year, Noctua showed us prototype coolers designed specicially for cramped Mini-ITX applications. Those prototypes have now become retail products: the NH-L9a and the NH-L9i. Both coolers stand just 1.46" (37 mm) tall: 0.91" (23 mm) for the heatsink and another 0.55" (14 mm) for the included fan. The L9a is sized for AMD sockets, while the L9i is an exact fit for Intel ones. Neither cooler branches out from the socket area, so they shouldn't conflict with adjacent memory or expansion slots.
As one might expect, these coolers have limitations. They're designed to dissipate only 65W, which means you shouldn't strap one to AMD's new FX processors. The NH-L9x series should be pretty quiet, though. The associated NF-A9x14 fan features rubberized mounting points, a magnetic bearing, a custom PWM controller, and a host of little touches intended to improve airflow and reduce noise levels.
Like Noctua's other products, the NH-L9x series doesn't come cheap. Expect to pay $48 for the coolers, which should be available starting today. Six-year warranty coverage is included, which at least makes the price tag a little easier to swallow.