Ripple Measurements
You will see the ripple levels we measured on the main rails of the CMX850 in the following table. The limits are, according to the ATX specification, 120 mV (+12V) and 50 mV (5V, 3.3V, and 5VSB).
Ripple Measurements Cougar CMX850 |
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Test | 12 V | 5 V | 3.3 V | 5VSB | Pass/Fail |
20% Load | 19.7 mV | 21.6 mV | 28.3 mV | 10.2 mV | Pass |
40% Load | 31.6 mV | 23.5 mV | 29.0 mV | 11.4 mV | Pass |
50% Load | 33.1 mV | 24.8 mV | 23.9 mV | 16.0 mV | Pass |
60% Load | 39.4 mV | 28.6 mV | 29.8 mV | 18.1 mV | Pass |
80% Load | 52.3 mV | 29.9 mV | 37.7 mV | 27.1 mV | Pass |
100% Load | 73.9 mV | 42.7 mV | 41.8 mV | 43.0 mV | Pass |
110% Load | 83.0 mV | 43.4 mV | 42.1 mV | 50.7 mV | Fail |
Crossload 1 | 25.4 mV | 23.5 mV | 30.7 mV | 12.6 mV | Pass |
Crossload 2 | 75.5 mV | 38.3 mV | 44.8 mV | 32.0 mV | Pass |
Ripple suppression was never this OEM's (HEC/Compucase) favorite area, and we can't help but wonder why they still struggle to produce good ripple suppression while other, more recently established OEMs already provide great working solutions in this area. The values shown on the table above may be inside ATX specifications, with the only exception being 5VSB during the overload test, but those values are still well above what we expect from a modern PSU. Cougar should pay more attention to the DC quality, implementing new methods that will effectively filter ripple at DC outputs.
Ripple at Full Load
You can see the AC ripple and noise that the main rails registered (+12V, 5V, 3.3V, and 5VSB) in the following oscilloscope screenshots. The bigger the fluctuations on the oscilloscope's screen, the bigger the ripple/noise. For all measurements, we set 0.01 V/Div (each vertical division/box equals 0.01 V) as standard.
Ripple at 110% Load
Ripple at Crossload 1
Ripple at Crossload 2