Conclusion

Anyone who has read about Seasonic on the Internet has almost certainly seen comments about their good quality, high efficiency, and extremely quiet designs. After testing two of the latest models we can definitely validate these comments. The S12II is one of the best power supply series on the market, sufficient for all but the most demanding systems. By looking at the lowest and highest rated models, we wanted to show the full range of what Seasonic offers with their new S12II series.

While there are many similarities between the two units, however, they still cater to different market needs. The small version is very attractive for users looking at mATX or HTPC computers for the living room where silence is the primary concern and a large power draw often isn't necessary. The 500W model can serve that market as well, but it can also support a decent high-end system and is only limited by the two PEG connectors it offers. As long as you don't need to run HD 2900 XT CrossFire or 8800 GTX SLI, there is very likely a Seasonic S12II that can fit your needs.

Efficiency Comparison

Efficiency Comparison

In the efficiency comparison we show the highest measured result of each tested unit. Both the largest and smallest Seasonic S12II power supplies score an 85% efficiency rating using a 230VAC input. For the most common loads, regardless of input voltage efficiency should still stay above 80%.

The DC outputs were good and stable, and we found very little to complain about with either unit. The cables of both units are of reasonable length with up to 80cm of the 500W version. The 330W version has slightly shorter cables and offers a wide range of connectors with a maximum length of 65cm. given that it's highly doubtful anyone would be looking to place the 330W version into a big tower, the length of the cables is not a problem; in fact, for use in small boxes and HTPC systems the shorter cable lengths are even preferred. The 330W version offers a single 6-pin PEG connector capable of handling anything up to a moderate high-end GPU. The bigger version has two 6-pin PEG connectors, one of which can also function as an 8-pin PEG connector. This is sufficient for powering more moderate SLI/CrossFire configurations, or for running a single top-end graphics card.

Anyone searching for a very silent power supply with good quality and performance will find the S12II series very attractive. They have delivered the lowest noise levels out of any power supplies we've tested so far, with the 500 model reaching a maximum noise level of only 28dB(A) -- practically silent, even in a worst-case scenario. Keep in mind that this kind of low noise is only possible through the use of a very slow turning fan. In the test we measured up to 1350 RPM with the 330W version and up to 1850 RPM on the 500W model. Slow turning fans do not move much air through the power supply, and that means in a poorly designed power supply you would get incredibly high temperatures and likely high failure rates. However, this doesn't apply with the S12II since the heatsinks stay relatively cool and Seasonic uses high-end components rated for up to 105°C. Having high-efficiency certainly helps.

Finally, let's take a look at the prices, and unfortunately this is the one area that will cause many users to think twice. Seasonic power supplies are definitely not cheap, especially considering the power ratings. The S12II 500W sells for around $110, and while we couldn't find the S12II 330W (we could only locate the older S12 330W), the S12II 380W starts at around $63 -- plus shipping, of course. Prices are similar in Europe, and in Germany we found prices of €82 ($114) and €46 ($64), excluding the shipping. Users will need to give careful thought to whether or not the features and performance offered can justify the price. For users looking to build a really silent system, the answer is a resounding yes. Even if silence isn't your primary concern, however, Seasonic's power supplies are definitely worth your money.

Temperatures, Fan Speed and Acoustics
Comments Locked

21 Comments

View All Comments

  • Zds - Wednesday, September 19, 2007 - link

    Good review on a good product.

    What seemed a bit misleading, tho, was the statement about suitability of these models to dual-gpu machines. I know many marketing guys favor the "bigger is better", but it would not hurt to you, too, clearing out that the 330W model is powerful enough for practically any single-socket-single-GPU machine, and most of the dual-GPU ones, too and the 500W should be enough for almost any single-CPU-dual-GPU machine..

    And as most of the modern machines (C2D/Athlon, not P4) spend most of their time at idle, and most of them idle at 60-100W, the 330W model saves not just your ears, but real money, as you can run the machine at the sweet spot almost all of the time.
  • gochichi - Sunday, September 16, 2007 - link

    I have to say that Seasonic is not a flashy brand, like Antec or something. It's more of a truly better product, it doesn't rely on its name I don't think. Do a lot of people really know this name?

    From my experience, Antec is just plain average quality with a lot of marketing dollars ... and while I would buy Antec again, I wouldn't choose it over most other brands. In fact, I'd generally avoid it, as 2 Antec PSs burned out on me and 0 of any other brand, even duck brand ones haven't failed on me.

    My Seasonic 330W is going strong for 2 years now and my system isn't exactly barebones although this power supply kept me away from the vulgar video card options.

    While I'm tempted by the performance features of 8800's and 2900s, it's the elegance of power efficiency and silence that does the trick for me. After going through the very beginning of 3D acceleration, with the original Voodoo, I can attest to the fact that power hungry cards are best regarded as beta versions, as prototypes, as overclocked. As research and development, and priced for zealots.

    In any case, I understand going with more wattage on the powersupply, I would do so myself (mostly, b/c I like having different operating systems in different hard drives). But Seasonic is quiet, classy, quality stuff that deserves my recommendation.

    I would go as far as to call it an underdog brand, it's not Corsair, it's little mentioned in recommendations... but it's really good stuff. Seasonic is like delicious wine, in a world dominated by beer.
  • wibeasley - Saturday, September 15, 2007 - link

    The 330 version has been at newegg for at least a month. The "II" designation of the series isn't obvious from the title, but the box image shows it. The specifications show it as well, under the "Series" value.

    http://www.newegg.com/Product/Product.asp?item=N82...">http://www.newegg.com/Product/Product.asp?item=N82...
  • bryanW1995 - Friday, September 14, 2007 - link

    I'll take the 620 hx that I just paid 127 AR at mwave instead of 115 for the 550vx.
  • USAF1 - Friday, September 14, 2007 - link

    I'm still waiting to see a review of a Seasonic S12 Energy+ PSU. Seasonic claims a peak efficiency of 88%.
  • Christoph Katzer - Friday, September 14, 2007 - link

    Between that one and now are still around 20 other PSUs which are laying around here and want to be reviewed...
  • tynopik - Friday, September 14, 2007 - link

    several of the charts such as efficiency, PFC and noise should be done on a watts scale instead of a % load scale. This will enable a direct comparison between alternatives.

    If i have a 250W load, how does the efficiency and noise compare among the 300, 400 and 550W power supplies? It's impossible to tell currently
  • Christoph Katzer - Friday, September 14, 2007 - link

    For what are the tables of page 6 then?
  • tynopik - Friday, September 14, 2007 - link

    well yes i can figure out 50% load on a 500w PS is about 250w

    so yes it is 'possible' to compare numbers between different reviews, but certainly not easy

    and why use % load any ways? how is it relevant?

    convenience wise it sure would be handy to make, for instance, a single efficiency chart and a single noise chart with all power supplies that have been tested so far so you could see how they compare across the range of interest
  • Christoph Katzer - Friday, September 14, 2007 - link

    Sounds good with the comparison, have thought about it already for an upcoming price guide.

Log in

Don't have an account? Sign up now