Chill Innovation CP-700M: Quiet EU Power

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The noise level during the pre-test warmup with 65W load was a very modest 15 [email protected] The quality of the sound was smooth and benign, with just a trace of the typical ball bearing buzz — audible only from up very close. There might have been a trace of buzzing from the PSU but at such a low level as to be trivial. This is top acoustics, and although a few others are even quieter, the advantage may not be noticed in the context of noise from other components in the PC and from the ambient in the environment.

The fan speed was monitored via the 3-pin plug provided for this purpose, using a completely fanless lab PC running off an Intel X25-M solid state drive. This is a new lab system used mostly to test hard drives in the anechoic chamber. The CP-700M fan started at 645 RPM, then stabilized at 650.

Although the fan speed crept up incrementally as load was increased (by just 15 RPM to 680 RPM at 250W load), the noise level did not change until the 300W mark. At this point, with the fan about 900 RPM, the SPL rose to 17 [email protected] The overall noise character was smooth, mostly broadband, with a bit of growl. Beyond this load, the fan speed jumped quickly, reaching 1480 RPM at 400W. The 30 dBA SPL was mostly broadband, but not really what we'd describe as quiet any more. Interestingly, the maximum speed was only 1600 RPM, reached by 550W load, when the intake air temperature inside the test box reached over 35°C. The data entry for the 400W load shows just 33°C intake, however, because by the time the thermals and fan speed had stabilized, the cooling effect of the increased fan speed had lowered the internal temperature of the box.


Through the first half of the load testing — over four hours in total during which time the PSU was always on with the load steadily increasing to the rated output — there was no concern about overheating. The °C temperature rise through the PSU stayed modest, in single digits until 400W load.

Beyond 500W load, the combination of the slow fan in our test box and the slow fan in the CP-700M kept temperatures rising. Again, it's unlikely that the maximum load thermal results are all that important, but builders should keep them in mind if the system is going to push this PSU regularly to such high loads.

The question of how much heat is pushed into the PC case (or test, box in this case) via the slots on the output side of the CP-700M was not possible to answer. The internal temperature in the test box was perhaps slightly higher than with other PSUs at the same test loads, but then the slow fan at high power could well be responsible. If there is any effect , it seems very small. In a real system run hard for long periods, an optical drive directly in front of the PSU may get hotter than normal. The simple solution would be to leave the top optical drive bay empty and perhaps set it up as a vent.

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