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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).
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
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Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.
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Really poor unit. For one thing, the crossload performance is poor. Sleeve bearing fan with less reliability. 85C primary capacitor. Once again, another failed 3.3V transient response. Very high inrush current. Also, near worst of all, 140+mv of ripple on the 12V rail in CL2. Just really bad. And CL2 is a realistic scenario these days because those 3.3V and 5V rails don't do much anyway. FSP's soldering is clearly not the same as the nice soldering on their high end units.Reply
But my largest complaint would have to be voltage regulation (line regulation) under different load scenarios on page 6.
85C main cap doesn't bother me that much. It should get airflow from the fan so unless the fan dies (and if it does 105C cap isn't going to help much.) or it gets clogged with dust you should be ok. As for the CL test what do you expect? It's a group regulated design so that's going to happen. It's like buying a super duty truck and then complaining you don't get 30MPG in town. What I find more bothersome is they can't seem to sell you what they claim on the box. If it's not C6 or C7 ready and not a group reg design, why claim so? I wonder if they shipped the wrong unit?Reply
Outstanding review by Aris as always! :)Reply
If only the PSU itself was outstanding as well:ouch:
Looks like FSP is still mostly a second tier manufacture with those transient response and inrush... does it really hurt that much to put a shuntable thermistor like Seasonic and SuperFlower units have?Reply
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"
actually I am worried about the bulk cap, because 85C means that it has 4x times lower lifetime than a 105C cap.Reply
17839248 said:85C main cap doesn't bother me that much. It should get airflow from the fan so unless the fan dies (and if it does 105C cap isn't going to help much.) or it gets clogged with dust you should be ok. As for the CL test what do you expect? It's a group regulated design so that's going to happen. It's like buying a super duty truck and then complaining you don't get 30MPG in town. What I find more bothersome is they can't seem to sell you what they claim on the box. If it's not C6 or C7 ready and not a group reg design, why claim so? I wonder if they shipped the wrong unit?
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?
It was already explained by Aris at his review:Reply
"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)
Not sure how the motherboard could shut down before the PWR_OK signal is dropped.Reply
the problem is that in some PSUs, PWR_OK, which informs the mainboard when it should shut down, drops after and not before the rails go our of spec. So once it drops the rails are already too low.Reply
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.
So is "DC_LOSS" considered "voltages out of spec"? I mean, there can still be DC even if voltages are out of spec. It won't be a loss of DC< just an out-of-spec voltage relative to the DC.Reply