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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.  

This time we made more detailed tests, starting from 85 W and increasing load little by little until we could see the maximum amount of power we could extract from the reviewed unit.

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. During this test the +12VA input was connected to the power supply “+12V1” rail, while +12VB was connected to the power supply “+12V2” rail (EPS12V connector).

Input Test 1 Test 2 Test 3 Test 4 Test 5
+12VA 3 A (36 W) 3.5 A (42 W) 4.5 A (54 W) 5.5 A (66 W) 6.25 A (75 W)
+12VB 2.5 A (30 W) 3.25 A (39 W) 4 A (48 W) 5 A (60 W) 6 A (72 W)
+5V 1 A (5 W) 1 A (5 W) 1.5 A (7.5 A) 1.5 A (7.5 A) 2 A (10 W)
+3.3 V 1 A (5 W) 1 A (5 W) 1.5 A (4.95 W) 1.5 A (4.95 W) 2 A (6.6 W)
+5VSB 1 A (5 W) 1 A (5 W) 1 A (5 W) 1 A (5 W) 1 A (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 84.6 W 99.2 W 124.4 W 147.8 W 172.7 W
% Max Load 15.4% 18.0% 22.6% 26.9% 31.4%
Room Temp. 41.6° C 41.2° C 41.1° C 41.5° C 41.9° C
PSU Temp. 44.9° C 44.9° C 44.9° C 44.9° C 45.1° C
Voltage Regulation Pass Pass Pass Pass Pass
Ripple and Noise Pass Pass Pass Pass Pass
AC Power 123.3 W 139.8 W 169.8 W 197.1 W 227.5 W
Efficiency 68.6% 71.0% 73.3% 75.0% 75.9%
AC Voltage 116.2 V 116.0 V 115.7 V 115.4 V 115.2 V
Power Factor 0.638 0.643 0.655 0.664 0.673
Final Result Pass Pass Pass Pass Pass
Input Test 6 Test 7 Test 8 Test 9 Test 10
+12VA 7.5 A (90 W) 8.25 A (99 W) 9.25 A (111 W) 10 A (120 W) 11 A (132 W)
+12VB 7 A (84 W) 8 A (96 W) 9 A (108 W) 10 A (120 W) 11 A (132 W)
+5V 2 A (10 W) 2.5 A (12.5 W) 2.5 A (12.5 W) 3 A (15 W) 3 A (15 W)
+3.3 V 2 A (6.6 W) 2.5 A (8.25 W) 2.5 A (8.25 W) 3 A (9.9 W) 3 A (9.9 W)
+5VSB 1 A (5 W) 1 A (5 W) 1 A (5 W) 1 A (5 W) 1 A (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 198.7 W 223.5 W 246.5 W 270.9 W 293.5 W
% Max Load 36.1% 40.6% 44.8% 49.3% 53.4%
Room Temp. 43.2° C 44.2° C 45.2° C 46.5° C 45.4° C
PSU Temp. 46.0° C 46.7° C 47.6° C 48.9° C 49.9° C
Voltage Regulation Pass Pass Pass Pass Pass
Ripple and Noise Pass Pass Pass Pass Pass
AC Power 259.1 W 290.4 W 318.4 W 349.4 W 378.6 W
Efficiency 76.7% 77.0% 77.4% 77.5% 77.5%
AC Voltage 114.6 V 114.1 V 113.6 V 113.1 V 113.3 V
Power Factor 0.679 0.685 0.687 0.693 0.697
Final Result Pass Pass Pass Pass Pass
Input Test 11 Test 12 Test 13 Test 14 Test 15
+12VA 12 A (144 W) 13 A (156 W) 14 A (168 W) 15 A (180 W) 16 A (192 W)
+12VB 11.75 A (141 W) 12.75 A (153 W) 13.5 A (162 W) 14.5 A (174 W) 15.5 A (186 W)
+5V 3.5 A (17.5 W) 3.5 A (17.5 W) 4 A (20 W) 4 A (20 W) 4.5 A (22.5 W)
+3.3 V 3.5 A (11.55 W) 3.5 A (11.55 W) 4 A (13.2 W) 4 A (13.2 W) 4.5 A (14.85 W)
+5VSB 1 A (5 W) 1 A (5 W) 1 A (5 W) 1 A (5 W) 1 A (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 318.2 W 340.5 W 364.4 W 386.9 W 412.6 W
% Max Load 57.9% 61.9% 66.3% 70.3% 75.0%
Room Temp. 44.5° C 46.6° C 48.5° C 45.7° C 47.3° C
PSU Temp. 46.9° C 48.5° C 50.6° C 52.3° C 54.3° C
Voltage Regulation Pass Pass Pass Pass Pass
Ripple and Noise Pass Pass Pass Pass Pass
AC Power 411.5 W 442.9 W 474.0 W 506.0 W 543.0 W
Efficiency 77.3% 76.9% 76.9% 76.5% 76.0%
AC Voltage 113.4 V 112.6 V 112.7 V 112.3 V 112.1 V
Power Factor 0.702 0.703 0.705 0.708 0.710
Final Result Pass Pass Pass Pass Pass
Input Test 16 Test 17 Test 18 Test 19 Test 20
+12VA 17 A (204 W) 18 A (216 W) 19 A (228 W) 20 A (240 W) 21 A (252 W)
+12VB 16.5 A (198 W) 17.25 A (207 W) 18.5 A (222 W) 19 A (228 W) 20 A (240 W)
+5V 4.5 A (22.5 W) 5 A (25 W) 5 A (25 W) 5.5 A (27.5 W) 5.5 A (27.5 W)
+3.3 V 4.5 A (14.85 W) 5 A (16.5 W) 5 A (16.5 W) 5.5 A (18.15 W) 5.5 A (18.15 W)
+5VSB 1 A (5 W) 1 A (5 W) 1 A (5 W) 1 A (5 W) 1 A (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 435.4 W 458.7 W 484.3 W 503.4 W 549.4 W
% Max Load 79.2% 83.4% 88.1% 91.5% 99.9%
Room Temp. 44.3° C 47.1° C 44.8° C 45.5° C 49.4° C
PSU Temp. 50.9° C 54.2° C 46.7° C 47.0° C 51.2° C
Voltage Regulation Pass Pass Pass Pass Fail on +12 V
Ripple and Noise Pass Pass Pass Pass Pass
AC Power 576.0 W 613.0 W 651.0 W 688.0 W Fail
Efficiency 75.6% 74.8% 74.4% 73.2% Fail
AC Voltage 111.2 V 110.8 V 110.5 V 110.1 V Fail
Power Factor 0.713 0.715 0.717 0.720 Fail
Final Result Pass Pass Pass Pass Fail

Cooler Master eXtreme Power Plus 550 W burned while we tried to pull 550 W from it at high temperatures.

Efficiency was always below 80%, varying between 73.2% and 77.5%, depending on the load.

Voltages were always within the allowed range.

And noise and ripple levels were always low. Below we publish the results for the test 20 (550 W), however it is important to notice that noise levels jumped from the ultra-low 25.2 mV at +12VA on test 19 to 78.4 mV on test 20. The same thing happened with the other outputs (noise level at +5 V jumped from 18.8 mV to 43.6 mV, for example). The maximum allowed is 120 mV on +12 V outputs and 50 mV on +3.3 V and +5 V outputs. All numbers are peak-to-peak figures.

Cooler Master eXtreme Power Plus 550 W RS-550-PCAR-E3 power supplyFigure 15: +12VA input from load tester at 549.4 W (78.4 mV).

Cooler Master eXtreme Power Plus 550 W RS-550-PCAR-E3 power supplyFigure 16: +12VB input from load tester at 549.4 W (88.2 mV).

Cooler Master eXtreme Power Plus 550 W RS-550-PCAR-E3 power supplyFigure 17: +5 V rail with power supply delivering 549.4 W (43.6 mV).

Cooler Master eXtreme Power Plus 550 W RS-550-PCAR-E3 power supplyFigure 18: +3.3 V rail with power supply delivering 549.4 W (12.2 mV).

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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.