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Testing Results, Maximum Fan Speed

Our maximum speed testing is performed with both the fans and the pump of the kit powered via a 12V DC source. This input voltage should have the pump and fans matching the speed ratings of the manufacturer. According to ARCTIC’s P14 PST fan specifications, the fans should have a maximum rotational speed of 1900 RPM. Our tachometer indicated that the fans were rotating at an average speed of exactly 1880 RPM, very close to their rated specifications.

The ARCTIC Liquid Freezer III 280 mm has an average thermal resistance of 0.075 °C/W with its fans running at maximum speed, outperforming most similarly sized offerings in terms of raw thermal performance, especially older products. Although its raw thermal performance seems to be barely matching that of the older and smaller Liquid Freezer II 240 mm model, the Liquid Freezer III is significantly quieter under the same operating conditions.

The Sound Pressure Level (SPL) of the ARCTIC Liquid Freezer III 280 mm with all of its components running at maximum speed is 40.4 dB(A), which is a good figure, yet it could have been better. Having a dedicated VRM fan plays a role here, as it contributes to the overall SPL level of the entire setup.

Testing Results, Low Fan Speed

Using a PWM voltage regulator, we reduced the speed of the fans manually down to half their rated speed. At this setting, the 140 mm fans of the Liquid Freezer III 280 mm rotate at 950 RPM. Note that this also affects the speed of the pump and VRM fan as well.

The high mass of the radiator gives the Liquid Freezer III 280 mm a strong advantage here, with its average thermal resistance rising to just 0.0836 °C/W. Its thermal resistance is fairly stable regardless of the load, suggesting a good thermal transfer design, despite its small contact plate. This places ARCTIC’s latest 280 mm cooler in direct competition with 360 mm AIO coolers and even close to the 420 mm version of the Liquid Freezer II, which used to perform a little better but at a much higher noise level.

With the fans at half speed, the noise levels drop to 33.1 dB(A), a figure that may not be as low as that of other similarly sized products that were engineered toward quiet operation, yet it is perfectly comfortable for even the most sensitive of ears. Under typical conditions, it should be nearly impossible for a user to discern the sound coming from the Liquid Freezer III 280 mm.

Thermal Resistance VS Sound Pressure Level

During our thermal resistance vs. sound pressure level test, we maintain a steady 100W thermal load and assess the overall performance of the coolers by taking multiple temperature and sound pressure level readings within the operating range of the stock cooling fans. The result is a graph that depicts the absolute thermal resistance of the cooler in comparison to the noise generated. For both the sound pressure level and absolute thermal resistance readings, lower figures are better.

This chart is highly revealing regarding the overall performance of the Liquid Freezer III 280 mm, with the cooler having one of the smallest inclinations we have ever seen. What that translates to is that the thermal performance of the Liquid Freezer III 280 mm is only slightly affected by the speed of the cooling fans. At first sight, this would suggest that the size of the heat exchange area is disproportionally low compared to the cooler’s capability to transfer thermal energy from the CPU to the radiator – however, manipulating the speed of the fans also affects the speed of the pump, which should play a significant role to the rate of transfer between the block and the radiator. From the above, we can only surmise that the contact plate is what limits the overall performance of the Liquid Freezer III 280 mm, which does perform very well under typical conditions but has little-to-no room for further improvement. 

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