Differential Temperature and Noise Levels

To simulate a demanding environment, some of the warm exhaust air from the PSU under test is recirculated back to the intake through a passive air duct, which allows the PSU air inlet temperature to increase with load, up to 40°C.  

The differential temperature across the power supply was calculated by subtracting the internal case air temperature (T in) from the temperature of the warm exhaust air flowing out the back of the power supply (T out).  

Thermocouples were placed at the air inlet and exhaust outlet. The ambient room air temperature was 23ºC (74ºF) +/- 0.5ºC during testing.

T out = temperature of air exhausting from power supply
T in = temperature of air entering power supply
Delta T = T out – T in

Sound pressure level readings were taken 3’ away from the rear of the case in an otherwise quiet room.  The ambient noise level was ~28 dBA.  

Note: Both EVGA SuperNOVA P2 power supplies were tested with the ECO Intelligent Thermal Control System switched Off (disabling fan-less operation) so we could take SPL measurements during load testing with the fan running.

SuperNOVA 650 P2:

SuperNOVA 750 P2:

With the ECO Intelligent Thermal Control System disengaged (silent mode and cooling mode only) both PSUs were virtually silent at low to mid power levels. Once the cooling fan started to speed up at the 75% load test, the noise was still barely noticeable. At full load with an elevated ambient temperature, the P2 PSU cooling fan did speed up and the noise became noticeable.

(Courtesy of EVGA)

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