Great review (as always)! I have two questions:

Judging from the recordings, the S12II-380 seemed more quiet and less "aggressive" than the VX450, but both measure 21 dBa at low loads. Is there a noticeable difference? Which would you say is quieter below 200W?

Do you expect the Seasonic to have identical noise profiles (i.e. same noise at same loads) as one or more of its siblings, or do you think they are all different? I ask because the "old" Corsair HX520 & HX620 were identical.

Thanks!

hmm.... I hear it in the recordings too. It could be a matter of slight differences in mic position. Try listening with the volume level set where the first 6 seconds of background noise is barely audible.

I'll try listening directly between the two PSUs -- and make another recording to double check on this.

I don't think there is an audible difference, but perhaps that plastic baffle is imparting some acoustic signature that I didn't notice before.

Will report back later.

OK, I tried listening to samples of the VX450, the S12II380 and the S12II500. There were small difference in the sound of each at minimum start level, but nothing that could be attributed to the plastic -- ie, the turbulence noise was the same, what I was hearing seem to be slight variances in fans. The fans in the VX450 and the S12II500 sounded closer to each other -- but this is only with my ear within about 6 inches from the exhaust vent. From a meter, there were no audible difference. I'm still not sure why the recordings show as marked a difference as it does.

Getting back to the question of whether the Seasonics will have the same acoustic signatures, yes, at least until close to the maximum load. The 500 and the Corsair VX450 should be about the same -- they both have that plastic baffle. So the S12II430 should be quieter than the VX450/S12II500 at very high loads.

There are fan differences in some of these models but for the VX versus S12II the fan is the same.

Fan Voltage at idle Brand/Model
4.5 Seasonic S12 rev 1
4.3 Seasonic S12 rev 2 (note this is the sleeved version not the roman numeral II version that is newer)
4.2 Antec Earth Watts
4.12 Seasonic S12-II
4.1 Antec Neo HE
4.06 Corsair VX
3.9 Seasonic M12
3.84 Corsair HX
3.8 Seasonic E+ and the old 500/600 watt S12

Notice the SPCR voltage reading is lower on the VX than it was for the S12II. Now is that within a margin of error and/or manufacturing variance?

Either way I'd make the choice based on the capacitor rating difference 85c vs 105c, and the efficiency curves. If you are the type to undervolt get a low wattage S12II, if you are the type to overclock get the VX 450 or the HX 520. If you aren't going to do either your choices are wide open...

Thank you very much Mike for doing the extra research and answering my questions! And thanks dhanson for the fan voltages, very informative!

This forum is incredible ...

yes. I suspect the latter -- the readings were very consistent and the multimeter is very accurate.

It’s great to finally see a low noise P/S that is efficient at low loads and inexpensive; thanks for the review.

Good to know i bought the right PSU :p. Im using it right in the sweet spot too - 150W-200W (folding 24/7)

From the pictures in the article it seems that the annoying internal exhausts are no longer present in the Seasonic S12II-380.
Is this correct? They were present in all the Seasonics I can remember, but not in Antec and Corsair PSUs built by Seasonic.

Mike and his fellow reviewers get all the credit. I just harvested that data from the SPCR reviews.

It is nice to see the march of progress to lower idle voltages.

Fan Voltage at idle Brand/Model
4.5 Seasonic S12 rev 1
...
...
...
3.84 Corsair HX
3.8 Seasonic E+

There is no doubt the fan controllers are quite a bit different between the first rev of the S12 and all the modern PSUs coming out in the last year.

I purchased the 330 recently and was disappointed by the fan noise - the loudest source in the case after stopping all other fans. Although it's significantly quieter than the CM380 it replaced, it's noticably louder than the 520HX. I'm looking forward to the comparison to see if it's just sample variance before I consider another purchase.

As far as efficiency, probably not surprisingly, the idle usage dropped 10w from the CM380; 84 -> 74.

Am I to take it that the 330 S12-II model doesn't have the beefier heatsinks of its higher wattage brethren, just as in the original S12 series? (thereby, requiring more airflow)

No, don't assume that. We haven't seen a S12II-330 yet, and the difference in the original S12 models only showed up under pretty heavy load. jackylman seems to be commenting mainly on the residual noise -- unlike that he'd stop all the fans in the system at load.

The pictures of the S12II models I have seen (330W, 380W and 500W) tend to indicate that they all use the same design and heatsinks. The obvious differences appear to be in the coils and capacitor sizes. From the photos, I cannot tell if they are using different semiconductor parts. The reviews here and at anandtech, also indicate that the fan speed profiles are different. If the only difference is the coils and capacitors, I would not expect a huge difference in cost between models.

If the designs are basically the same, the power rating may be limited by the over current protection settings on each model. The heatsink temperatures appear to be very similar for the 330W and 500W at the same output loading. At higher output powers, the larger supplies will have correspondingly higher heatsink and transistor junction temperatures.

I just ordered a S12-330 supply and received a S12II-330 in its place. I am trying to decide if I should keep the series II supply or return it and look for an original model. I prefer the layout of the original design (PWM and OCP components on main board and AC input connectorized). However, the series II is undoubtably more efficient and also ROHS compliant. I am only running a basic machine Semprom 28000+, 512M RAM, on board video, single HDD and DVD drive. Any thoughts?

Red.

The S12-380 I bought a year ago was also RoHS compliant. That seems to have been introduced when they sleeved the cables (first half of 2006)

Your machine should run ~40-50W wall power as measured by a Kill-A-Watt or Power Angel when browsing and 60-75W when testing with BurnK7. You will never, ever stress a 380W PSU with your system. I have a Sempron 2800+ system just like yours, although I'm in the process of moving to AM2 to get the more advanced fan control on newer mobos such as the Abit AN-M2.

this review has convinced me in buying this power supply, and i am very satisfied with it!

i just bought one to replace my dead liberty... i'm actually quite disappointed... i've never had the benefit of a SLM, so i didn't know what 21dB actually sounds like. until now...

the 380 isn't loud or anything... but it is definitely louder than my old fan-swapped liberty...

what if u change adda fan with nexus?
will that make the diference in lowering the noise? did anyone tried that?

actually i did that... swapping but something happened, because the artic cooling fan i have put in doesn't want to start , n or the adda fan; how can i find out what is the problem?

I bought a Seasonic S12II-380 about a year ago, on the strength of this review.

I am very happy with it, apart from one thing, which has only now become a real problem for me: I do not think it actually gives out its rated output.

My HTPC will not boot when I have two HDDs installed. When I try to start it, the CPU cooler starts for about two seconds, and then turns off, and then tries restarting after another two seconds. This goes on repeating. I noticed this when I first built my HTPC, but now that I actually want a second drive in the machine permanently, it's a problem.

I even built the machine to be electrically efficient, with a C2D E4300, onboard Intel graphics and just 2GB of RAM. The only things added on are a dual-tuner DVB-T TV card, an Asus Xonar soundcard and the case's iMon LCD display (Antec Fusion Black). It refuses to boot with two HDDs even when these things are disconnected.

The HTPC idles at 75W with one HDD, and it does run with a second HDD when I connect it after the machine has booted. Is there some way I can automatically do a staggered startup like this?

How come this 380W PSU cannot handle my modest hardware? I have an HP ProLiant ML115 G5 server which came with a 375W PSU (it's relatively noisy though) which can boot perfectly fine with four HDDs, a SAS controller card and a dual NIC card.

Jason404 -- that's abnormal. I'd return it for a replacement.

Thanks. I have been trying to RMA it, but the company that used to distribute Seasonic PSUs in the UK (Nanopoint) no longer do it, and I have been having problems getting in contact with Seasonic in Holland.

In the mean time I have bought a Silver Power 400W PSU that Nanopoint say is made by Seasonic.