Efficiency, Differential Temperature and Noise


Efficiency is defined by the power output divided by the power input and is usually expressed as a percentage.  If a PSU were a 100% efficient (which none are) 600 watts of AC power going in would result in 600 watts of DC power coming out (with no waste heat to dissipate).  In the real world there are always inefficiencies and power is lost in the form of heat during the conversion process. Newer revisions to the ATX12V Power Supply Design Guide V 2.2 have continued to increase the efficiency recommendations for PC switching mode power supplies and now lists both required and recommended minimum efficiencies.

We measured the AC power input to the PRIME 600W Fanless PSU with an Extech power analyzer while the total DC load was found by adding all the individual +3.3V, +5V, +12V, -12V and +5VSB loads together.  

The overall efficiency of the power supply was again excellent and easily meets the rigorous standards for 80 Plus Titanium certification.

80 Plus Program

    Note: Tests conducted at room temperature (25°C)

Differential Temperature and Noise Levels

We tested the PRIME 600W Fanless power supply on an open bench, not inside an enclosure. Thermocouples were placed above (T out) and beside (T in) the PSU. The ambient room air temperature was 23ºC (74ºF) +/- 0.5ºC during testing.

T out = temperature of air above the top of the power supply
T in = temperature of room air
Delta T = T out – T in

The PSU was silent with no indication of audible coil whine. I could actually feel the warm air flowing out the top of the power supply (via natural convection) at 100% load. Because this is a fanless PSU, it needs to be installed in a case with very good airflow.

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