ASUS Silent Square Pro: Compact Embedded-Fan Heatpipe Tower

Noise

For many enthusiasts upgrading cooling the goal is maximum stable overclock, and they will live with the inconvenience of a louder system. For other users silence is the most important factor, and these users will forgo maximum overclocking if that increases system noise levels.

There are virtually no power supplies that do not include a fan. While Zalman and a few others do make an expensive fanless power supplies, we have not seen a fanless unit larger than 500W, or one that would be used for seriously overclocking a system. With that in mind the noise level of the system with all fans turned off except the power supply was measured. The power supply used for the cooling test bed was the OCZ PowerStream 520, which is one of the quieter of the high performance power supplies.

We have also measured the Corsair 620-watt and Mushkin 650-watt power supplies which are reported to be quieter than the OCZ. Both the Corsair and Mushkin are indeed quieter at idle or start up speed. However, as soon as load testing begins and the PSU fan speed kicks up the measured noise level is almost exactly the same as the OCZ PowerStream 520 watt power supply.

We are currently in the process of evaluating "quieter" power supplies for an update to our cooler test bed. We will make changes to that test bed as soon as we are confident in the noise measurements and test procedures with a variable speed quiet PSU. We plan to evaluate additional power supplies and configurations in our upcoming 120mm fan roundup, at which point we will complete the transition to a revised and lower noise cooler test bed.

The noise level of the power supply was 38.3 dB from 24" (61cm) and 47 dB from 6" (152mm). The measured noise level of the test room is 36.4 dB, which would be considered a relatively quiet room with a noise floor slightly below the OCZ PowerStream 520 PSU.

We measured noise levels with the ASUS Silent Square Pro under both load and idle conditions. Results were then compared to the system noise floor. The fan did not have a specified noise rating, but we suspected higher noise levels than we typically find with the better 120mm fans. The smaller 90mm fan in the Silent Square Pro turns at 1020 RPM on lowest speed and it turns at a much faster 2500 RPM at full speed. These are much higher fan speeds than we typically see in 120mm fans and a sleeve bearing fan is not likely to hold down the noise from the increased fan speeds.



Measured noise levels in this chart should be considered worst case. Measurements were taken with an open side of a mid tower case 6" and 24" from the HSF. Real world would be a completely closed case resulting in a further reduction in noise.

At the minimum speed of 1020 RPM the measured noise at 6" and 24" is below the system noise floor. However, minimum speed does reduce cooling efficiency with idle cooling increasing from 30C to 33C and load cooling increasing to 48C from the max speed 42C. Cooling at lower speeds is not as good, but the system still will run fine all day long at stock speeds with the low-speed fan. Don't, however, expect to overclock much with the fan on minimum.

At the maximum rated speed of 2500 RPM (measured 2280 RPM) noise is above the system floor. Even at idle the 44.6 dB-A noise from the fan will be heard. It is even more pronounced under load at full fan speed with a 51.3 dB-A rating. ASUS calls this cooler the Silent Square Pro, but it is reasonably silent only with the fan speed and cooling efficiency turned way down. At rated fan speed the ASUS Silent Square Pro can definitely be heard in your system.

The odd 90mm fan size makes finding a fan to improve noise performance unlikely. The fan is a standard 25mm thick so it may be possible to replace the fan with a better one if you can find a better 90mm fan. The fan mounts in the center of the cooler.