Now let’s take a look at the acoustic measurements:
Unfortunately, Zalman CNPS9900 LED is not a quiet cooling solution even at its minimal fan rotation speed. Despite the low dBA levels on the diagram (33.2 at 1m and 1000 RPM), the cooler generates low-frequency rumbling sound. The constantly changing fan rotation depending on the CPU utilization speed also adds certain discomfort. Even when doing common things in Photoshop or during archiving, Zalman CNPS9900 LED fan speeds up and slows down all the time. Believe me, it is much more annoying than a monotonous humming of the fan at high rotation speed. However, in absolute numbers Zalman CNPS9900 LED turned out quieter than Zalman CNPS9700 NT.
Summing up the results of our today’s test session I would like to say that the new Zalman cooler outperformed its predecessor, Zalman CNPS9700 NT, having proven quieter and more efficient. Yes, it is $25 more expensive and yields in combined key characteristics, such as cooling efficiency and acoustic performance, to the etalon solution from Thermalright. However, Zalman CNPS9900 LED boasts ideally even base finished with remarkable quality, offers an LGA 1366 retention kit with it and directs the airflow along the mainboard PCB (to be exhausted out of the system case).
On our part, we would like to make a few recommendations to Zalman for their next (still hypothetical) cooler revision: to make the plastic fan housing solid, use a 38-mm fan and replace automatic PWM rotation speed adjustment with a manual one, like the one used in Zalman CNPS9700 LED. All this added to impressive looks and bright LED glow will make the new solution extremely attractive, especially with such great holidays as Christmas and New Year just around the corner. Happy holidays! :)