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Replacing the Case Fans

After powering the PC down, I replaced the two 120mm Akasa fans with a pair of self-regulating AcoustiFan ‘Ultra-Quiet’ clear case fans, costing £19.98 each. The AcoustiFans regulate their own speed using a thermal sensor that can be positioned inside the computer case, either close to or at some distance from the fan itself. Airflow through the case is then adjusted automatically as required to minimise the noise where possible.

As part of their low noise design, the AcoustiFans use low vibration sleeve bearings in the fan motor. Each fan also comes with four gel fan mounts that can be, if required, fitted into the fan mounting holes to reduce the noise caused by vibrations that get transmitted through the case. Fan speed is rated at 1500-2500rpm depending on temperature although this can be slowed down even further using the supplied low speed in-line resistor.

Initially though, the two quiet fans were fitted straight onto the plastic case brackets and connected directly to the 12V supply, as I wanted to assess what effect a direct swap would have on the overall noise levels. In fact, we couldn’t use the gel mounts with these fans even if we wanted to because the fan mounting holes on the C6607 chassis are a little over 120mm wide, hence the screwless plastic brackets.

It’s also worth noting that the AcoustiFans are fitted with three-pin motherboard connectors, so if your motherboard doesn’t have any spare fan headers, you’ll have to buy an appropriate adaptor and take power directly from a spare 12V PSU lead instead.

Once powered up again, the reduction in noise from the PC was clearly discernable. The overbearing drone of the two Akasa fans was now replaced with a much more subtle low frequency humming sound. According to the BIOS, the fans were spinning at 1400rpm, which was slightly slower than their minimum rated speed. This translated into an overall noise reduction of between 5 and 7dB(A), depending on the orientation of the case.

However, I do believe there is some potential scope for a further noise reduction. The perforated hexagonally shaped openings at the front fan inlet and rear fan outlet on the C6607 case are not the ‘cleanest’ of designs. This type of obstruction to the airflow will certainly not be helping matters and is probably the main cause of the tonal noise that is still audible with the AcoustiFans. A better solution would be a thin wire grille design, similar to the those sometimes found on PSUs (see also the photo of the Zalman PSU later in this feature).

Nevertheless, in just a matter of minutes I managed to achieve quite a significant reduction in noise for a relatively small cost. Surprisingly, the BIOS reported no change in the system temperature from before, which remained at a constant 27 degrees C. The CPU temperature also remained the same at 35 degrees C.

Because the overall noise level dropped so markedly after replacing the two case fans, I could now also hear some tonal fan noise coming from the PSU at the rear of the case. I decided the next step should be to replace this with a ‘noiseless’ Zalman ZM400B-APS 400 watt power supply.

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