Is it just me, or does this seem to be the exact same unit that SeaSonic makes for Corsair's HX line?

Have you seen an HX430 yet? I don't, and that is the reason why I bought non-modular when my NeoHE 430 failed. I think it's a good addition to the market.

Nice review, thanks SPCR!
Since this is a Seasonic, the good performance is normal.
Which leaves the only relevant question: DOES IT BUZZ?

Seems to be the exact same design yeah. But didn't Corsair get it's PSU's from Seasonic, or the other way around?

Hello,

SeaSonic makes PSU's, for themselves and for Corsair, among others.

1) SeaSonic might be rating their PSUs more conservatively than Corsair
2) It might be made with lower rated components on the same PCB

These points are eglible for the VX450/S12II430 comparison, but I think not for the M12II/HX comparison (in the review, there's something said about capacitor rating which looked quite good)

Well, if you get close enough to any power conversion product, you'll find they all buzz. The real question is how audible is the buzzing.... and how easily is a PSU provoked into buzzing. The answer to the first is that if we didn't comment on it, it didn't have audible buzzing. The answer to the second can only be answered with many users and many samples. Finally, this is the kind of thing where small samples variances may have an unfortunately large impact.

Fair enough, thank you. At least your sample didn't buzz.
You do indeed need many samples to find out how bad sample variance is, buzz-wise.
I wonder if the 105C rated capacitors make it a better candidate for fan swap.
I was thinking about swapping the fan in my S12E+650 with a Slipstream, which BTW still aren't available in my country.
But since my Seasonic buzzes, I must first find a definite non-buzzer and do the fan swap on that one.

A safe fan swap is all about total power draw -- if it's low enough, you can run fan at a constant <500rpm and be perfectly safe in a decent system setup. Too little airflow in a high power system will cause some component in the PSU to eventually fail from overheating. I've done this a few times with ~300W models over the years, using hardwired slow/quiet 5V fans.

This definitely looks like a great low power modular psu. I love the efficiency and noise levels at low wattages.

There are two minuses that would push me toward recommending the HX series though. One is the price is not much lower than a HX520. Second, the fan ramp starts at 200w, while the HX series starts after 300w. While almost all systems will idle under 200w, a serious gaming system can exceed that wattage on load.

I assume the "baffle" is there for a reason.. but it looks like it blocks half the fan area! It looks like patchwork design. It must be cheaper than designing the unit so the heat sinks are in the natural airflow path.

It's not a question of whether the HS are in the airflow path. The 120mm fan PSU design has a fundamental flaw; all of these PSUs have the same problem -- some of the airflow from the fan is wasted, as it slips out the vent without doing any cooling.

You could avoid this by making a longer case and position the fan farther from the opening. Or you could use a baffle. The end result is better cooling overall w/o having to run the fan as fast. If you were running the fan hard all the time, the baffle would not be needed -- but then the noise...

The price of the baffle in this M12II? Probably higher turbulence noise at higher fan speed... but note that we did not hear anything different from other top rated Seasonic-made PSUs w/o this baffle. At low fan speed, the baffle is acoustically insignificant.

Don't exaggerate, btw, it's nothing like half -- as noted in the review, the baffle covers about a quarter of the fan opening.

I realize they are trying to "point" the air at the back of the unit, away from the exhaust, but I think we can agree that a fan with a "baffle" must move less air than one without. I'm no expert, but it's not obvious to me that this would provide better cooling at the same noise level. It looks like it'd be ready to vibrate like mad, and make lots of noise. It was clear the reviewer thought it was an improvement, however, and I believe you if you say it doesn't.

The plastic is very stiff and small, it never really vibrates, you can't hear that even with the fan at full tilt. I think you can here more whooshing.

I've discussed this technique with Seasonic (and other company) techs -- they say it does reduce component temps. The airflow is forced further back into the "dead" zones of the PSU before blowing out, compared to just going straight out.

Not all this aerodymics stuff is obvious.... even for the geniuses in these forums.

Mike, when you talked to them, have they mentioned anything about making a 380w version of the same?

Oof, I've gotta say the M12-II has the steepest fan curve of the modern lineup. It actually looks closer to the fan curve of the Earthwatts series.

While i understand 120mm fan'd PSU's are "all the craze", couldnt you also get better cooling while keeping noise low by using an 80mm fan mounted on the front of the psu, pushing air over the components and then out the back?

Although it would probably make the modular plugs closer together on the back.

Its definately got a place in the market, but i still think the corsair 520 is the clear choice for low noise. Its not that much more than this unit, but stays quiet up to a much higher load.

Yes, I think so, but people and companies usually move like lemmings or schools of fish. 80mm fans are still made by various -- including Seasonic -- but virtually no one is selling retail packaged versions of any.

@Aris: Felger Carbon's and Bluefront's tests clearly show that a fan can much easier overcome impedance behind it than in front.
So for a single 80 mm fan to push air through the PSU you'd need a 80x38 mm one, Arctic Cooling sells such fans IIRC.
About a year ago I submitted the idea of two 80 mm fans pushing air through the PSU, and IIRC MikeC agreed it was a good idea.
Of course, the PSU would have to be a bit wider than the standard, and the connectors might have to come through the bottom.
But it seems that no PSU seller is willing to spend 2$ more for an extra 80 mm fan.

also bear in mind that with fans in series, you don't get any extra CFM, just more static pressure, and with something like FSP's Green Power, there is not much impedance, so not much benefit. cluttered power supplies might benefit more.

Hello,

To add a comment about the baffle -- it allows the back of the case to be essentially sealed with no openings, and they eliminated the need for the 60mm fan. The fan could be scooched all the way towards the back of the unit, away from the opening, and that might help, too.

It seems that 'two 80 mm fans pushing' wasn't clear enough for some people, so I'll clarify this:
These two fans wouldn't be *in series*, one pushing, the other pulling, but *in parallel*, side by side. So you would get twice the CFM, or less noise.
Because two 80 mm fans *in parallel* take more space, the PSU would have to be a bit wider than the standard.
Also, because the two fans would take all the space at the back of the PSU, the cables would have to come through the bottom.

it isn't immediately apparent that 2 80mm fans in parallel will have a better CFM/dB ratio than a single (good) 120mm, also there is the negative aspect that it makes the PSU non-ATX compliant.

Nice Review.Lol.

Isn't the new plastic "baffle" going to cause dust to accumulate inside the housing? BTW, what is the best way to clean the dust bunnies out of these PSUs?