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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 6 A (72 W) 13 A (156 W) 19 A (228 W) 25.5 A (306 W) 32 A (384 W) +12VB 6 A (72 W) 13 A (156 W) 19 A (228 W) 25.5 A (306 W) 31.5 A (378 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 164.4 W 344.1 W 506.8 W 680.8 W 846.7 W % Max Load 19.3% 40.5% 59.6% 80.1% 99.6% Room Temp. 45.3° C 45.3° C 46.8° C 49.5° C 46.0° C PSU Temp. 51.4° C 51.6° C 52.4° C 54.7° C 52.6° C Voltage Regulation Pass Pass Pass Pass Pass Ripple and Noise Pass Pass Pass Pass Pass AC Power 181.2 W 376.9 W 559.8 W 765.0 W 972.0 W Efficiency 90.7% 91.3% 90.5% 89.0% 87.1% AC Voltage 116.7 V 114.7 V 112.6 V 110.4 V 107.9 V Power Factor 0.992 0.991 0.995 0.996 0.997 Final Result Pass Pass Pass Pass Pass

The XFX PRO 850 W Black Edition Full Modular presented outstanding efficiency, always above the minimum set by the 80 Plus Gold certification. 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.

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.