Differential Temperature and Noise Levels
To simulate real world operation, some of the warm exhaust air from the PSUs under test were recirculated back to the intake through a passive air duct, which allows the PSU air inlet temperature to increase with load, just like it would in a real PC.
The differential temperature across the power supplies were 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 power supplies were tested with the ECO Intelligent Thermal Control System switched ON (enabling fan-less operation at low to mid power levels).
SuperNOVA 750 G2:
SuperNOVA 750 G2:
*Fan not rotating
With the ECO Intelligent Thermal Control System engaged, both PSUs operated in silent, fan-less mode at low to mid power levels. Once the cooling fan did start to spin the noise was noticeable but not loud. At full load the 850 G2 PSU cooling fan kicked into high speed and although I was not able to take a SPL reading, the fan noise was subjectively loud.
(Courtesy of EVGA)
I was not able to take SPL measurements at the higher loads due to the background noise created by all the programmable DC load cooling fans running. At the low to mid power test loads I am able to catch a moment when all the load fans have cycled off to take a SPL reading of just the PSU fan.