Since there is no software included with the Silent Loop, we have to adjust the Fan header's power settings via either the Bios or the ASUS AI Suite. If we ran the PWM AUTO profile the RPM of the fans at Idle was around 865 RPM, picking up rapidly to full blast when the processor was loaded with the Prime95 stability test benchmark. Therefore we include three readouts in this article when we tested the Overclocked setup:

• Silent Loop with the fans at full speed +/- 2000 RPM (1)
  
• Silent Loop with auto adjusted fixed fan speed at 70%: +/-1525 RPM (2) (barely audible)
• Silent Loop with adjusted fan speed at 50%: +/- 1125RPM (3) (inaudible)

However before we start off with the heavy pounding, a quick test at stock speeds of the hexacore i7-3960X. Keep in mind that on the ASUS Rampage IV Black Edition motherboard,  the Intel i7-3960X is not running according the stock Intel Turbo, but runs at 3900MHz on all the cores when being loaded.

Without a surprise the Be Quiet Silent Loop goes straight head to head with the best of the pack. For the stock CPU tests we left the two fans hooked up to the CPU PWM and observed no rpm higher than 1500rpm in the AIDA64 software, meaning the Silent Loop 240 has no issue cooling down our little hexacore 3960X monster and still has room for a higher OC. This while remaining barely audible, which is great for daily gaming usage.

Time to let the i7-3960X rip at 4500MHz through the Mersenne Prime95 benchmark. The included air coolers have a hard time keeping the temperatures of the processor near the 80°C mark. Depending on the fan profile chosen most AIO's are near the 72-75°C when the Silent or Quiet profile is selected. At Idle we don't observe much between the different fan profiles, the Be Quiet Silent Loop does a great job. We didn't expect anything else from a copper radiator did we?

Even with the 3960X overclocked to 4500MHz the Be Quiet remains well in control of the six cores crunching at Prime95. Even with the copper radiator it can't match the performance of the bigger 280 powerhouses from Cooler Master and Corsair, but it has to be stated the former generate a lot more noise. There's a 6°C difference between the fans at 1100rpm or running flat out at 2000rpm. For the tweakers and benchers, these might be vital though for a daily gaming or encoding rig it is negligible. Looking at the noise measurement we can spot that the Pure Wings 2 are barely audible at 1500rpm and below, so they truly live up to the name of Be Quiet, providing a good mixture of good cooling performance yet at a balanced noise level. Them extra 2-3°C better cooling performance isn't worth the extra 8dBA in my book. Coolness assured at quiet sound levels, that is what these Silent Loop AIOs are all about !