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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 and +12VB inputs were connected to the power supply’s single +12 V rail. (The +12VB input was connected to the power supply EPS12V connector.)

 Input Test 1 Test 2 Test 3 Test 4 Test 5 +12VA 5 A (60 W) 10 A (120 W) 14.5 A (174 W) 19 A (228 W) 23.5 A (282 W) +12VB 5 A (60 W) 10 A (120 W) 14 A (168 W) 19 A (228 W) 23.5 A (282 W) +5 V 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) 1.5 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 140.4 W 272.9 W 394.2 W 527.4 W 652.4 W % Max Load 21.6% 42.0% 60.6% 81.1% 100.4% Room Temp. 47.3° C 46.4° C 47.1° C 49.3° C 48.9° C PSU Temp. 47.9° C 47.7° C 48.0° C 49.3° C 49.2° C Voltage Regulation Pass Pass Pass Pass Pass Ripple and Noise Pass Pass Pass Pass Pass AC Power 154.8 W 298.2 W 435.8 W 593.3 W 755.0 W Efficiency 90.7% 91.5% 90.5% 88.9% 86.4% AC Voltage 116.8 V 115.4 V 114.2 V 112.8 V 110.6 V Power Factor 0.972 0.978 0.986 0.992 0.994 Final Result Pass Pass Pass Pass Pass

The 80 Plus Gold certification promises efficiency of at least 87% under light (i.e., 20%) load, 90% under typical (i.e., 50%) load, and 87% under full (i.e., 100%) load. The Fractal Design Tesla R2 650 W was able to match these numbers for light and typical loads at high temperatures. At full load we saw 86.4% efficiency, a tad below the minimum promised. However, the AC voltage dropped to below 115 V, which might explain this number. Also, as we always point out, the 80 Plus tests are conducted at 23° C, and we test power supplies at higher temperatures.

Let’s discuss voltage regulation 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.