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Load Tests

We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.  

First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load.

If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.

The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. Since this power supply in reality has only one +12 V rail (see explanation in the previous page), both inputs were connected to the single rail present. The +12VB input was connected to the power supply EPS12V connector, while other connectors where installed on the +12VA input.

Input Test 1 Test 2 Test 3 Test 4 Test 5
+12VA 4 A (48 W) 7.5 A (90 W) 11 A (132 W) 14.5 A (174 W) 18 A (216 W)
+12VB 3.5 A (42 W) 7.5 A (90 W) 11 A (132 W) 14.5 A (174 W) 18 A (216 W)
+5V 1 A (5 W) 2 A (10 W) 4 A (20 W) 6 A (30 W) 8 A (40 W)
+3.3 V 1 A (3.3 W) 2 A (6.6 W) 4 A (13.2 W) 6 A (19.8 W) 8 A (26.4 W)
+5VSB 1 A (5 W) 1 A (5 W) 1.5 A (7.5 W) 2 A (10 W) 2.5 A (12.5 W)
-12 V 0.5 A (6 W) 0.5 A (6 W) 0.5 A (6 W) 0.5 A (6 W) 0.5 A (6 W)
Total 110.4 W 205.3 W 313.6 W 417.2 W 520.1 W
% Max Load 21.2% 39.5% 60.3% 80.2% 100.0%
Room Temp. 44.1° C 43.8° C 44.9° C 47.3° C 45.9° C
PSU Temp. 45.0° C 45.2° C 46.0° C 48.1° C 50.3° C
Voltage Regulation Pass Pass Pass Pass Pass
Ripple and Noise Pass Pass Pass Pass Pass
AC Power 129.4 W 237.3 W 365.9 W 494.6 W 631.0 W
Efficiency 85.3% 86.5% 85.7% 84.4% 82.4%
AC Voltage 114.2 V 113.2 V 111.8 V 110.5 V 108.9 V
Power Factor 0.996 0.996 0.997 0.997 0.996
Final Result Pass Pass Pass Pass Pass

Seasonic S12II Bronze 520 W can really deliver its labeled wattage at high temperatures.

Efficiency was very high all the times, staying between 85.3% and 86.55% when we pulled up to 60% of the power supply labeled wattage (i.e., up to 312 W). At 80% load (416 W) efficiency was still high at 84.4%. And when delivering its full 520 W the reviewed unit achieved 82.4% efficiency. Therefore this unit can really maintain the 80 Plus Bronze minimum requirements under real-world temperatures. If you follow our reviews you know by now that not all 80 Plus-certified power supplies can deliver the efficiency that they promise because 80 Plus certification is done at a room temperature of only 23° C and efficiency drops with temperature.

Voltages regulation is another highlight from Seasonic S12II Bronze 520 W: all voltages were closer to their nominal voltages than required, staying within a 3% tolerance, while ATX12V specification allows a 5% tolerance. This includes the -12 V output.

And noise and ripple were amazingly low, as you can see below. The maximum allowed is 120 mV for the +12 V output and 50 mV for the +5 V and +3.3 V outputs. All numbers are peak-to-peak figures.

Seasonic S12II Bronze 520 W power supplyFigure 15: +12VA input from load tester at 520.1 W (22.8 mV).

Seasonic S12II Bronze 520 W power supplyFigure 16: +12VB input from load tester at 520.1 W (21.0 mV).

Seasonic S12II Bronze 520 W power supplyFigure 17: +5V rail with power supply delivering 520.1 W (11.6 mV).

Seasonic S12II Bronze 520 W power supplyFigure 18: +3.3 V rail with power supply delivering 520.1 W (18.4 mV).

Let’s see if we can pull more than 520 W from this unit.

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Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.