Power supplies which employ Power Factor Correction (PFC, or A-PFC) help ensure efficient conversion of AC to DC voltage, and reduce the amount of energy wasted as heat. That means a quieter 120mm fan can be used, and less noise for your ears.

PCSTATS tests power efficiency with the aid of an Extech Model 380803 Power Analyzer. The meter is located between the mains 120AC supply and the power supply, and a 120W dummy load is connected to the power supply being tested. Power jitter is measured with a Mastech MS8230B Multimeter at the device power connectors. The test apparatus and power meters are shown below.

The power supply looking device is actually the 120W dummy load. To the right is a standard Voltmeter, and in the background the Extech Model 380803 Power Analyzer (with readings for Watts, PFC/KHz, source voltage (AC) and Amperage).

Power Jitter Observations - Motherboard

Voltage jitter is read by accessing the power options displayed in the motherboard BIOS, with the system obviously in an unloaded state. *All voltages were read from the BIOS of an Asus BLITZ EXTREME motherboard.

Power Jitter Observations - Motherboard
Listed Voltages	Lower Voltage	Upper Voltage	Jitter
+3.3V	3.3V	3.3V	0V
+5.0V	5.0V	5.0V	0V
+12V	12.00V	12.00V	0V

The voltage readings within the motherboard BIOS do not move one bit. These values are very good.

Power Jitter Observations - Multimeter

Voltage jitter was read by a Mastech MS8230B Multimeter with the system in an unloaded state. During testing the power supply is was still connected to a full computer and voltage values.

Power Jitter Observations - Multi-Meter
Listed Voltages	Lower Voltage	Upper Voltage	Jitter
+3.3V	3.3V	3.3V	0V
+5.0V	5.0V	5.0V	0V
+12V	12V	12V	0V

Readings with the multimeter are also rock solid, like we would have ever doubted PC Power & Cooling... ;-)

Seasonic Load Tests	Source: Seasonic

When looking at the Seasonic Power Supply test results we see two values, wattage and volt-amps. Since it might not be clear what they measure, here's a brief overview.

The volt-amp (VA) value is how much real power is being consumed by the power supply being tested to provide the wattage (W) value. The higher the VA value is, the more electricity is being used by the power supply. Because no electrical device is 100% efficient, there will always be some loss when converting AC to DC. The closer the volt-amps and wattage figures are to each other, the more efficient a power supply is. This is called the Power Factor: wattage / volt-amps =PF.

Since we're testing with a 120W dummy load, the load on the power supply (wattage) should be as close to this figure as possible. Anything above this load in apparent power describes the overhead and wasted energy (given off as heat) for the particular power supply being tested. For the unloaded tests, the wattage and volt-amp figures should be as close as possible to one another. The lower the figures are, the less power is being wasted.

Measurements were taken with an Extech 380803 Power Analyzer.

Seasonic Power Load Tests Power Supply Model Wattage Test Type Loaded Unloaded Seasonic SuperTornado 400 W (A-PFC) Active Power 177 W 6 W Apparent Power 182 VA 7 VA Vantec iON2 350 W Active Power 192 W 10 W Apparent Power 277 VA 21 VA Antec TruePower 330 330 W Active Power 195 W 22 W Apparent Power 289 VA 38 VA Ultra X-Connect Green UV 500W 500 W Active Power 193W 22 W Apparent Power 307 VA 40 VA AOpen Silent Power AO400-12AHN 400 W Active Power 179W 9 W Apparent Power 275 VA 18 VA Seasonic S12-430 430 W (A-PFC) Active Power 179W 6W Apparent Power 180VA 9VA PC Power and Cooling Turbo-Cool 510 Express/SLI 510 W (A-PFC) Active Power 200 W 29 W Apparent Power 202 VA 32 VA HEC Ace Power 580UB 580 W Active Power 183 W 12 W Apparent Power 272 VA 26 VA HEC Win 550UB 550 W Active Power 184W 10W Apparent Power 263VA 22VA Akasa PowerPlus AK-P550FF 550 W (A-PFC) Active Power 194W 38W Apparent Power 197VA 40VA AOpen Prima Power AO700-12ALN 700 W (A-PFC) Active Power 172W 3W Apparent Power 181VA 9VA PC Power & Cooling Turbo-Cool 1KW 1000 W (A-PFC) Active Power 205W 25W Apparent Power 207VA 32VA Seasonic S12 600 600 W (A-PFC) Active Power 164W 7W Apparent Power 173VA 9VA Mushkin Enhanced XP-650 650 W Active Power 192W 22W Apparent Power 279VA 43VA Seasonic S12 Energy Plus SS-650HT 650 W (A-PFC) Active Power 150W 7W Apparent Power 150VA 10VA Seasonic M12 700W 700 W (A-PFC) Active Power 161W 8W Apparent Power 165VA 11VA Corsair HX620W 620 W (A-PFC) Active Power 171W 8W Apparent Power 173VA 12VA Zalman ZM600-HP 600 W (A-PFC) Active Power 173W 5W Apparent Power 175VA 9VA HEC Zephyr 650 650 W (A-PFC) Active Power 185W 12W Apparent Power 190VA 17VA GlacialPower GP-PS550BP 550 W Active Power 178W 6W Apparent Power 269VA 17VA Cooler Master Real Power Pro 750W 750 W (A-PFC) Active Power 158W 6W Apparent Power 163VA 9VA Seasonic S12 II 500W 500W (A-PFC) Active Power 145W 7W Apparent Power 148VA 10VA Enermax Infiniti 720W 720W (A-PFC) Active Power 179W 12W Apparent Power 181VA 18VA COOLMAX GREEN POWER CUQ-1200B 1200W (A-PFC) Active Power 172W 9W Apparent Power 193VA 12VA PC Power & Cooling Silencer 750 Quad 750 (A-PFC) Active Power 168W 12W Apparent Power 175VA 15VA

The PC Power & Cooling Silencer 750 Quad is not quite able to reach 83% efficiency but that's mainly due to the fact that we're only putting the power supply under 120W of load. Generally speaking to reach 80+ efficiency, the power supply must have at least 20% load and in this case the PC P&C Silencer 750 Quad is only under 16.5% load. PCSTATS actively looking for gear to improve our load testing, so bare with us...

The final word is next.

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