Cooling Efficiency Tests

Using the “weakest” cooling system with the fan in quiet mode we managed to overclock our 45nm quad-core processor to 3.75GHz inside a closed system case. The processor Vcore was increased to 1.4875V in the mainboard BIOS:

The monitoring programs detected a slightly lower voltage setting than in the mainboard BIOS, around 1.45~1.47V:

The diagram below reveals the results obtained for our today’s testing participants in this case:

Let’s analyze the obtained results in order of appearance on the diagram (the same order as the coolers appearance in our today’s review). At first a few words about Noctua NH-U9B. This compact cooler equipped with one 92-mm fan working at ~1110RPM turned out not very efficient for an overclocked CPU, especially in a closed system case and pretty high room temperature. However thanks to the opportunity to use a second fan for air exhaust and to increase their rotation speed, Noctua NH-U9B improved its cooling efficiency by 9ºC in an open testbed and by 11ºC in a closed system case. Therefore we can say that the efficiency of this Austrian cooler depends a lot on the airflow going through the heatsink array. I would also like to add that 92mm fan at its maximum speed of ~1730RPM (according to monitoring utilities) doesn’t generate too much noise: it never goes past 35dBA (measured with a noise-meter at 1m distance). If the rotation speed is lower, you can barely hear the fan at all. The motor doesn’t crackle, too.

Our second testing participant, Thermalright Ultima-90I is actually the best of the three coolers discussed today. This cooler efficiency depends even more on the fan(s) rotation speed, because this heatsink array is denser than that of Noctua cooler. In the end, Thermalright Ultima-90I equipped with two 92-mm fans for air intake and exhaust rotating at ~1730RPM doesn’t fall too far behind Thermalright SI-128 SE, although the latter is working in a quieter mode in our today’s test session. As for the results Thermalright Ultima-90I demonstrated with a 120 x 120 x 25mm fan, there is nothing surprising about them. if we set both, 92- and 120-mm fans, at the same noise level using our noise-meter device (at ~900RPM and ~1450RPM respectively), Thermalright Ultima-90I will be identically efficient in both cases. That is why we decided not to overload our charts with additional results obtained with a 120-mm fan.

And finally, a few words about Zalman CNPS9300 AT. Only inside a closed system case this cooler performs as efficiently as Noctua NH-U9B with one fan working at ~1730RPM. IN an open testbed Zalman CNPS9300 AT falls pretty far behind its today’ rivals. It only manages to outperform their quietest operational modes. Besides, we also detected crackling of the fan motor, which you can hear even at the minimal rotation speed of ~1530RPM.