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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 how the reviewed unit behaved 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 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 and +12V2 rails, while +12VB was connected to the power supply +12V1 rail (EPS12V connector).

 Input Test 1 Test 2 Test 3 Test 4 Test 5 +12VA 2.5 A (30 W) 5.5 A (66 W) 8 A (96 W) 10.5 A (126 W) 14 A (168 W) +12VB 2.5 A (30 W) 5.5 A (66 W) 8 A (96 W) 10.5 A (126 W) 13 A (156 W) +5V 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 (5 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 A (5 W) 1.5 A (7.5 W) 2 A (10 W) 2 A (10 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 78.9 W 158.3 W 236.8 W 309.6 W 395.4 W % Max Load 19.7% 39.6% 59.2% 77.4% 98.9% Room Temp. 46.0° C 46.0° C 46.5° C 47.5° C 45.4° C PSU Temp. 51.9° C 51.5° C 51.1° C 51.8° C 52.4° C Voltage Regulation Pass Pass Pass Pass Pass Ripple and Noise Pass Pass Pass Pass Pass AC Power 101.3 W 195.8 W 296.4 W 398.1 W 539.0 W Efficiency 77.9% 80.8% 79.9% 77.8% 73.4% AC Voltage 114.9 V 114.4 V 113.4 V 112.2 V 110.5 Power Factor 0.559 0.624 0.645 0.66 0.673 Final Result Pass Pass Pass Pass Pass

Cooler Master Elite Power 400 W can really deliver its labeled power at high temperatures.

If fact we had a few good surprises with this unit.

Usually ultra low-end power supplies (i.e., cheap units) present efficiency way below 80%, but with this one efficiency was touching 80% when we pulled between 40% and 60% from its labeled capacity (i.e., between 160 W and 240 W). At full load, however, efficiency dropped to around 73%.

Voltage regulation was the highlight from this unit. All positive voltages were within 3% of their nominal values all the times, which is great, since the ATX12V specification allows a 5% tolerance for these outputs.

The only real problem with this power supply is the high noise and ripple levels, which is kind of expected on low-end units. Although high, they were still inside specs. During test five noise level at +12VA touched the 120 mV limit, as you can see below. The maximum allowed is 120 mV on +12 V and 50 mV on +5 V and +3.3 V. All these numbers are peak-to-peak figures.

Figure 13: +12VA input from load tester at 395.4 W (120.0 mV).

Figure 14: +12VB input from load tester at 395.4 W (113.4 mV).

Figure 15: +5 V rail with power supply delivering 395.4 W (30.6 mV).

Figure 16: +3.3 V rail with power supply delivering 395.4 W (27.6 mV).

Let’s see if this unit can deliver more than 400 W.

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.