"Noctua's NH-C14 is an overall good performer. It wasn't expected to do as well as the NH-D14, as it has less surface area on its radiator fins, but it wasn't far behind. Running at stock speeds, the two Noctua heatsinks were in line. With the increased heat load of the overclocked processor, the NH-C14 stayed within 2 degrees celcius of the larger NH-D14. When switching to one fan, temperatures only increased by 1 degree celcius. And while we didn't specifically test the RAM slots and the area around the CPU socket, there was a good amount of airflow in those areas with the NH-C14.
The NH-C14 CPU cooler was pretty quiet to our ears with both fans running. When using only one fan, it was very quiet. Inside of a decent case, I'd guess that it would be inaudible with a one fan setup. And performance wise, switching to one fan barely made a change in temperatures.
While I'd still recommend the NH-D14 over the NH-C14 due to its leading performance, the NH-C14 still has a place in the market. If clearance space is a concern, the Noctua's NH-C14 should be on your short list of CPU coolers to look at. Its design allows gives consumers more flexibility in the ability to use smaller cases or install high-profile RAM, but still retain a high level of thermal performance. It's highly recommended."
Brandon - CircuitRemix
Noctua NH-C14 CPU cooler review by CircuitRemix - Introduction & Conclusion. The mentioned Noctua NH-D14 is also available from Mittoni.