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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 the behavior of the reviewed unit 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 powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (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. In 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. During this test, the +12VA input was connected to the power supply +12V1 and +12V3 rails, while the +12VB input was connected to the power supply +12V2 rail.

Input Test 1 Test 2 Test 3 Test 4 Test 5
+12VA 5 A (60 W) 11 A (132 W) 16 A (192 W) 22 A (264 W) 27 A (324 W)
+12VB 5 A (60 W) 10 A (120 W) 16 A (192 W) 21 A (252 W) 27 A (324 W)
+5 V 2 A (10 W) 4 A (20 W) 6 A (30 W) 8 A (40 W) 10 A (50 W)
+3.3 V 2 A (6.6 W) 4 A (13.2 W) 6 A (19.8 W) 8 A (26.4 W) 10 A (33 W)
+5VSB 1 A (5 W) 1.5 A (7.5 W) 2 A (10 W) 2.5 A (12.5 W) 3 A (15 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 149.3 W 299.5 W 446.8 W 591.6 W 748.4 W
% Max Load 19.9% 39.9% 59.6% 78.9% 99.8%
Room Temp. 45.4° C 45.0° C 46.8° C 47.7° C 46.9° C
PSU Temp. 47.8° C 48.2° C 49.4° C 50.4° C 51.7° C
Voltage Regulation Pass Pass Pass Pass Pass
Ripple and Noise Pass Pass Pass Pass Pass
AC Power 165.7 W 330.2 W 498.5 W 674.0 W 868.0 W
Efficiency 90.1% 90.7% 89.6% 87.8% 86.2%
AC Voltage 116.2 V 114.5 V 112.9 V 110.4 V 109.1 V
Power Factor 0.984 0.996 0.998 0.999 0.999
Final Result Pass Pass Pass Pass Pass

The FSP Aurum CM Gold 750 W can really deliver its labeled wattage.

Efficiency was extremely high when we pulled between 20% and 60% of the labeled wattage (i.e., between 150 W and 450 W), ranging from 89.6% to 90.7%. At 80% load (600 W), efficiency dropped to 87.8%, still very high. And at full load (750 W), efficiency dropped to 86.2%, a little bit below the 87% minimum promised by the 80 Plus Gold certification. As we always must explain, tests for the 80 Plus certification are conducted at a room temperature of only 23° C, and we test power supplies above 45° C. (Efficiency drops with temperature.)

Voltage regulation was excellent, with all voltages within 3% of their nominal values, except for the -12 V output. (The -12 V output was inside the proper range.) This means that the positive voltages were closer to their nominal values than required by the ATX12V specification, which says positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values.

Noise and ripple levels were always below the maximum allowed, but a little too high at the +12 V outputs when the unit was delivering 750 W for us to consider this unit as “flawless.” Below, you can see the results for the power supply outputs during test number five. The maximum allowed is 120 mV for +12 V and -12 V outputs, and 50 mV for +5 V, +3.3 V and +5VSB outputs. All values are peak-to-peak figures.

FSP Aurum CM Gold 750 W power supplyFigure 19: +12VA input from load tester during test five at 748.4 W (68.4 mV)

FSP Aurum CM Gold 750 W power supplyFigure 20: +12VB input from load tester during test five at 748.4 W (81.2 mV)

FSP Aurum CM Gold 750 W power supplyFigure 21: +5V rail during test five at 748.4 W (36.4 mV)

FSP Aurum CM Gold 750 W power supplyFigure 22: +3.3 V rail during test five at 748.4 W (29.6 mV)

Let’s see if we can pull more than 750 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.