DC Load Regulation

Testing Methodology

Establishing an accurate load is critical to testing and evaluating a PC power supply.  PCPerspective’s power supply test bench can place a precise DC load on the PSU under test.  Each power supply is tested under controlled, demanding conditions up to its maximum rated load (at 40ºC), using both 115 VAC and 240 VAC line voltage.  Our current suite of tests includes:

•    DC Load Regulation
•    AC Ripple and Noise
•    Efficiency
•    Differential Temperature
•    Noise

The EVGA SuperNOVA 650 P2 and 750 P2 power supplies were evaluated on both features and performance.  A full range of equipment was used to test the power supply under controlled load conditions.  

•    (2) CSI3710A Programmable DC load (+3.3V and +5V outputs)
•    (4) CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
•    (2) 200W Precision resistor load bank (+12V5 and +12V6)
•    Switchable precision resistor load bank (-12V and +5VSB)
•    Agilent 34401A digital multimeter (Accuracy ±0.0035% vDC)
•    Extech 380803 Power Analyzer (Accuracy ±0.5% of full scale)
•    DS1M12 "StingRay" digital oscilloscope (20M S/s with 12 Bit ADC)
•    Powerstat Variable Autotransformer, 1.4 KVA, 0-140 VAC
•    Extech Model 407738 digital sound level meter (Accuracy ±1.5 dB)

The following cables/connectors were used to connect the two EVGA PSUs to the PCPerspective power supply test equipment.

EVGA SuperNOVA 650W P2:
•    (1) 20+4 pin ATX
•    (1) 8-pin EPS/ATX12V
•    (4) 6-pin PCI-E
•    (2) SATA
•    (2) Molex

EVGA SuperNOVA 750W P2:
•    (1) 20+4 pin ATX
•    (2) 8-pin EPS/ATX12V
•    (6) 6-pin PCI-E
•    (2) SATA
•    (2) Molex

DC Output Load Regulation

To simulate demanding and maximum loading conditions, the EVGA SuperNOVA 650 P2 and 750 P2 power supplies were connected to the load testers and supplied with a constant 115 VAC.  In this test we are interested in seeing how well a PSU can maintain the various output voltages while operating under different loads.  

The ATX12V V2.2 tolerance for voltages states how much each output (rail) is allowed to fluctuate and has tighter tolerances now for the +12V outputs.  I have also included a second table of expanded tolerances (±1% to ±6%) for reference.

SuperNOVA 650 P2: The following tables list the DC voltage results for the 650 P2 PSU while operating on 115 VAC, 60 Hz.

The 650 P2 produced excellent voltage regulation on all of the DC outputs with the measured values falling within ±1% on the three major rails!

SuperNOVA 750 P2: The following tables list the DC voltage results for the 750 P2 PSU while operating on 115 VAC, 60 Hz.

The 750 P2 also produced excellent voltage regulation on all of the DC outputs; nearly identical to the results we saw on the 650 P2.

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