Nexus Value 430 PSU: Affordable Silence

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7. NOISE and FAN CONTROL

The noise level during the pre-test warmup with 65W load was so low as to require a double-take. Was the PSU really on? Was the fan spinning? Up very close, a tiny bit of ticking and hum could be heard. The fan was indeed spinning, and a check with the calibrated strobe light showed it to be at 370RPM. This is the slowest of any fan in a PSU we've yet reviewed.

The sound level was measured to be about 11 dBA@1m, or a single decibel above the ~10 dBA noise floor of the anechoic chamber. The microphone picked it up from a meter away, but I could not hear it from a meter. I had to get within about a foot. Ditto Larry, who was also in the lab at the time of testing. This incredibly low noise level prevailed from 20W to above 150W load.

At 200W the SPL rose to a still barely audible 16 dBA@1m. The fan speed was measured to be 670RPM. The overall noise character was smooth, mostly broadband, a bit of hum, and barely audible ticking. The noise level went up incrementally to 18 dBA@1m at 250W load, then to 19 dBA at full power.


The difference with the PSU on at idle was barely one decibel.


The ambient curve looks different (from previous graph) because the vertical scale has been expanded. Still well under 20 dBA@1m even at 430W load.

These results were so surprisingly low that the microphone and SpectraPlus acoustic analysis system was recalibrated for accuracy twice, and the load test was repeated two more times at full load. The results were nearly identical every time.

8. COOLING

Throughout the course of the load testing — over three hours during which time the PSU was always on with the load steadily increasing to the rated output — I was concerned that the slow spinning fan would cause overheating in the PSU. Surprisingly, my concern was unfounded; the temperature rise through the unit remained under 5°C up to 250W load, and it reached a relatively modest 15°C at full power. Of couse, the total heat being generated in the PSU itself was only a touch over 100W.

The 10°C rise seen at 300W is probably the most relevant measurement: This PSU is not likely to be used in systems that draw any more than 300W. The single cooling fan in the test loader box was running at ~750 RPM at that load. It appears that the combination of good efficiency and minimal fan speed in both the PSU and the case will be enough to keep the PSU adequately cooled.

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 Value 430 was not possible to answer. The internal temperature in the test box was not any higher than with other PSUs at the same test loads, so if there is any effect , it seems very small. In a real system run 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.

NOTE: It is possible that the very low airflow of the Value 430 fan actually helps it achieve lower temperature rise numbers. Heat is generated in the test box, but because the airflow in the box is always low, it may not move up into the PSU that easily. Perhaps the slow speed of the PSU fan means it draws less of the test box heat into itself than a faster spinning fan might.



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