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## Ripple and Noise Tests

Voltages at the power supply outputs must be as “clean” as possible, with no noise or oscillation (also known as “ripple”). The maximum ripple and noise levels allowed is 120 mV for +12 V and -12 V outputs, and 50 mV for +5 V, +3.3 V and +5VSB outputs. All values are peak-to-peak figures. We consider a power supply as being top-notch if it can produce half or less of the maximum allowed ripple and noise levels.

The Fractal Design Tesla R2 650 W provided ripple and noise levels within specifications, as you can see in the table below. When we pulled 650 W from this unit, ripple and noise levels were too close to the maximum allowed at +5 V, +3.3 V, and +5VSB outputs.

 Input Test 1 Test 2 Test 3 Test 4 Test 5 +12VA 18.4 mV 27.4 mV 36.4 mV 37.2 mV 47.4 mV +12VB 18.6 mV 28.2 mV 37.0 mV 36.8 mV 46.0 mV +5 V 15.6 mV 17.0 mV 19.6 mV 27.4 mV 41.6 mV +3.3 V 16.4 mV 17.2 mV 20.2 mV 26.2 mV 42.8 mV +5VSB 15.4 mV 18.0 mV 22.4 mV 30.0 mV 47.8 mV -12 V 21.8 mV 41.4 mV 52.8 mV 45.6 mV 49.4 mV

Below you can see the waveforms of the outputs during test five.

Figure 24: +12VA input from load tester during test five at 652.4 W (47.4 mV)

Figure 25: +12VB input from load tester during test five at 652.4 W (46.0 mV)

Figure 26: +5V rail during test five at 652.4 W (41.6 mV)

Figure 27: +3.3 V rail during test five at 652.4 W (42.8 mV)

Let’s see if we can pull more than 650 W from this unit.

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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.