Ripple Measurements
To learn how we measure ripple, please click here.
The following table includes the ripple levels we measured on the L9-CM-600W's rails. The limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V and 5VSB).
| Test | 12V | 5V | 3.3V | 5VSB | Pass/Fail |
|---|---|---|---|---|---|
| 10% Load | 7.0mV | 10.4mV | 12.5mV | 10.6mV | Pass |
| 20% Load | 12.5mV | 12.0mV | 16.3mV | 12.7mV | Pass |
| 30% Load | 13.3mV | 13.5mV | 18.8mV | 13.4mV | Pass |
| 40% Load | 13.5mV | 13.7mV | 20.9mV | 15.1mV | Pass |
| 50% Load | 14.4mV | 15.4mV | 22.9mV | 9.7mV | Pass |
| 60% Load | 17.0mV | 17.0mV | 25.7mV | 10.7mV | Pass |
| 70% Load | 19.7mV | 18.8mV | 27.7mV | 11.3mV | Pass |
| 80% Load | 24.1mV | 23.5mV | 31.0mV | 12.3mV | Pass |
| 90% Load | 29.7mV | 26.4mV | 32.9mV | 14.3mV | Pass |
| 100% Load | 36.7mV | 30.4mV | 36.3mV | 14.9mV | Pass |
| 110% Load | 45.3mV | 38.1mV | 38.8mV | 18.0mV | Pass |
| Cross-Load 1 | 22.4mV | 47.8mV | 26.8mV | 18.1mV | Pass |
| Cross-Load 2 | 147.6mV | 38.3mV | 41.9mV | 39.5mV | Fail |
Ripple suppression under normal conditions is pretty good at +12V and 5VSB, and good enough on the minor rails. All hell breaks loose in the CL2 test though, and although the PSU manages to keep ripple under control for the most part, we still saw some spikes exceeding 120mV on the +12V rail. We should note that with 230VAC input we didn't notice any of these spikes. Most likely the increased efficiency allows for lower operating temperatures, so less stress is applied to the +12V circuit.
Ripple Oscilloscope Screenshots
The following oscilloscope screenshots illustrate the AC ripple and noise registered on the main rails (+12V, 5V, 3.3V and 5VSB). The bigger the fluctuations on the screen, the bigger the ripple/noise. We set 0.01V/Div (each vertical division/box equals 0.01V) as the standard for all measurements.
Ripple At Full Load
Ripple At 110-Percent Load
Ripple At Cross-Load 1
Ripple At Cross-Load 2
But my largest complaint would have to be voltage regulation (line regulation) under different load scenarios on page 6.
If only the PSU itself was outstanding as well:ouch:
For less than $10 more you can usually find excellent Seasonic and SuperFlower Leadex Gold units, which makes it really hard to say this PSU is anything more than "meh"
Not all group regulated designs are exactly the same way. We see in Seasonic's S12ii series a group regulated design that actually crossloads very well. This seems to be one of the worst on the ladder.
@Aris: Why is Inactive PWR_OK to DC_LOSS better at a higher value? Once the PWR_OK signal is dropped, wouldn't you want the unit to shut down as quickly as possible, not prolong it?
"The power-good signal lasts longer, so when it drops, the voltage level of the +12V rail is already below 11V."
When the pwr_ok to DC_loss is higher (*meaning that it has a positive , not negative value) that means that the motherboard will already have been shut-down. (*from what i've understand, at least)
Normally when AC is removed, the PWR_OK signal should be de-asserted at least 1ms before voltages go out of spec in order not to stress the VRMs of the mainboard and of other components (e.g. VGA, HDD, SSD, etc.).
The only way to address this issue is to have a circuit on the mainboard checking the input voltages and give the shut down order when these go out of spec. In other words to completely bypass the power_ok signal coming from the PSU. But this will cost money and after all a PSU oughts to follow ATX spec's guidelines.