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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 rail, while the +12VB input was connected to the power supply +12V2 rail.

 Input Test 1 Test 2 Test 3 Test 4 Test 5 +12VA 4 A (48 W) 8 A (96 W) 12 A (144 W) 16.5 A (198 W) 20 A (240 W) +12VB 4 A (48 W) 8 A (96 W) 12 A (144 W) 16 A (192 W) 20 A (240 W) +5 V 1 A (5 W) 2 A (10 W) 4 A (20 W) 5 A (25 W) 6 A (30 W) +3.3 V 1 A (3.3 W) 2 A (6.6 W) 4 A (13.2 W) 5 A (16.5 W) 6 A (19.8 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 113.5 W 215.7 W 328.4 W 436.4 W 548.6 W % Max Load 20.6% 39.2% 59.7% 79.3% 99.7% Room Temp. 45.4° C 44.8° C 44.4° C 44.3° C 48.0° C PSU Temp. 50.6° C 49.9° C 49.9° C 50.5° C 52.9° C Voltage Regulation Pass Pass Pass Pass Pass Ripple and Noise Pass Pass Pass Pass Pass AC Power 134.5 W 249.4 W 381.5 W 516.9 W 664.0 W Efficiency 84.4% 86.5% 86.1% 84.4% 82.6% AC Voltage 118.7 V 117.8 V 116.5 V 115.1 V 113.7 V Power Factor 0.965 0.979 0.988 0.992 0.994 Final Result Pass Pass Pass Pass Pass

The Enermax NAXN 82+ 550 W passed our tests with flying colors.

Efficiency was between 82.6% and 86.5% during our tests. As you know, there are several power supplies with the 80 Plus Bronze certification that can’t deliver 82% efficiency at full load under high temperatures.

Voltage regulation could be a little better, but was not bad at all for an entry-level unit. In the table below, we show which outputs were outside the tighter 3% range we like to see to consider a power supply “flawless.” The outputs that were within three percent of their nominal values were labeled “≤ 3%.” All voltages were still inside the proper range. The ATX12V specification states that positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values.

 Input Test 1 Test 2 Test 3 Test 4 Test 5 +12VA ≤ 3% ≤ 3% ≤ 3% ≤ 3% +11.57 V +12VB ≤ 3% ≤ 3% ≤ 3% ≤ 3% +11.57 V +5 V +5.18 V +5.17 V ≤ 3% ≤ 3% ≤ 3% +3.3 V ≤ 3% ≤ 3% ≤ 3% ≤ 3% ≤ 3% +5VSB ≤ 3% ≤ 3% ≤ 3% ≤ 3% ≤ 3% -12 V -11.45 V -11.52 V -11.60 V -11.63 V ≤ 3%

Let’s discuss the ripple and noise levels on the next page.

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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.