"Noctua always seems to impress. Each time they come out with a cooler it has a specific purpose and it always accomplishes that goal. For the NH-U9S their goal was to make a high-performance CPU cooler that would still fit in small systems. They were able to accomplish this. It is not often that you find a CPU cooler that guarantees that there will be no clearance issues with memory or PCI-Express cards, even on mini-ITX motherboards."
Bob Buskirk - ThinkComputers.
Noctua NH-U9S CPU cooler review by ThinkComputers - Introduction & Conclusion.