It has been 16 months since our last power supply review, but the long wait is finally over. We have a new PSU and cases editor, and this is the first of many new PSU reviews to come. The first PSU to hit our new testing lab is the S12G 650W from Seasonic. Seasonic is a company that hardly requires any introduction; they are one of the oldest and most reputable computer PSU designers, manufacturers and retailers. Today, their products are held in very high regard by experts and enthusiasts. The company has their own retail range but they also serve as an ODM for many other well-known brands.

The target groups of the S12G series are advanced users, enthusiasts, and generally those who are not afraid to pay a bit more for advanced performance. It has impressive specifications and features, including an 80 Plus Gold efficiency certification and a "Smart and Silent Fan Control", as well as a five-year manufacturer's warranty. Despite that, it does not really break the bank, as the 650W version that we will be testing today retails for $89.99 plus shipping, a price that appears quite reasonable for such a product.

A year or two ago, you would have had a hard time trying to find a high quality 80 Plus Gold certified unit for that kind of price; however, today Seasonic's retail range has tight competition from several other manufacturers, such as Antec, EVGA, Rosewill, and others. As the Seasonic S12G is not a modular unit and doesn't really include any special features, the company clearly relies on quality and performance above all else; middling quality and average performance cannot be tolerated when several other manufacturers are breathing down your neck. Let us see if the 650W version of the S12G can live up to Seasonic's reputation.

Packaging and Bundle

Seasonic supplies the S12G PSU inside a fairly well designed cardboard box, with a black/blue color theme. The front of the box is tidy, with just a few badges with the certifications of the unit on display. The sides and rear of the box however are littered with information about the unit, in several languages.

Companies rarely supply anything noteworthy alongside their PSUs, especially the non-modular models, but the Seasonic S12G appears to be an exception. Besides the usual power cord, manual, and screws, Seasonic also includes a few cable ties, three blue/black velco cable straps, and a case badge with the company's logo.

The Seasonic S12G 650W PSU
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  • E.Fyll - Saturday, March 1, 2014 - link

    That will happen too. Companies (and consumers) generally favor large PSUs at the moment and there are very few high performance, low wattage models. I certainly do not plan on testing high output units alone though, neither focusing on just a single "class" of products. Patience, I can only do one at the time. In time, there will be a good variety of reviews, of every output/range/class.
  • pandemonium - Friday, February 28, 2014 - link

    Nice read. I went for the big brother instead about a month ago when my Corsair TX650 decided enough was enough:
  • Talcite - Saturday, March 1, 2014 - link

    Glad to see PSU reviews have returned!
  • CknSalad - Saturday, March 1, 2014 - link

    There's a 360 watt version of this Seasonic brand line. Honestly anything 660/7870 and less just get a quality 360-400 watt psu so your efficiency is also decent under non-gaming/non-intensive loads. 550 watt for a high end single-gpu system (Titan/780 TI/290/290x). GPUs in between those mentioned above a quality 450w psu is good enough.
  • FriendlyUser - Saturday, March 1, 2014 - link

    I applaud the newer testing methodology for cases and PSUs. Great job.
    I am a fan of Seasonic PSUs and have been buying them for a few years. Since I started using Seasonic PSUs I have observed a very low component failure rate for my HD, GPUs etc. Maybe because of very low ripple or because of excellent voltage regulation? Anyway, worth investing in a high-end PSU.
  • E.Fyll - Saturday, March 1, 2014 - link

    Indeed. Most people do not realize that but power quality (ripple/noise suppression mostly) is, in my opinion, by far the most important aspect of a PSU. It hardly affects the performance of the PSU itself but it has a dramatic impact on the longevity and reliability of your system's components.

    Do not be fooled however, low ripple does not mean low noise; you can easily have a low ripple signal with horrible levels of noise in it. We can only present ripple readings at the moment. We will get a super-fast oscilloscope that can filter noise out of a ripple signal soon; until then try not to confuse these two figures please.
  • FriendlyUser - Saturday, March 1, 2014 - link

    Thanks for the clarification. I really want to see noise figures for PSUs. I would also be curious to see if PSU quality affects analog sound output quality in a measurable way. That would be a cool comparison to make in the future, if you have access to the measuring instruments.
  • tynopik - Saturday, March 1, 2014 - link

    Performance when the current is normal and all the components are behaving nicely is boring.

    We want real torture tests!

    - What happens to the output in either severe brownout or overvoltage conditions? What happens when the input is unstable and bounces all over the place? Hook that sucker up to a variac and play with the knob like you're a DJ.

    - Transient analysis- aka does the output remain in spec when 10 hard drives spin up at once

    - Over-current protection- What happens if a component shorts? What if it just draws a lot more power than it should? Can you melt a cable? Can you blow a fuse? Can you hurt other components on other cables?
  • FriendlyUser - Saturday, March 1, 2014 - link

    Torture tests are only meaningful, in my opinion, if they correspond to possible usage scenarios. Although interesting, the performance of a PSU in situations that will almost never arise should not influence a buying decision.
  • E.Fyll - Saturday, March 1, 2014 - link

    And I want a high output, high frequency, programmable AC power source. Do you happen to have 20.000 USD to spare? ;)

    The VARIAC (oh, I am using one) is entirely useless for the tests that you mentioned. Simply "rotating the knob" is entirely wrong. I will be adding such tests in the future, when I have better equipment available.

    As for most of the last tests that you mentioned, these cannot be tested. They are assumptions and performing any one of such "tests" will damage the components of a PSU indefinitely, rendering it useless. For example, if I short the rectifier bridge, it will permanently damage it and probably other components of the PSU as well. Unless you can supply me with 100 units of each model, I cannot test what would happen if every given component would fail.

    Oh, and if the distibution grid around your area shifts like "a DJ is rotating the knob", which is not really possible (infinite bus theory), you need to complain to the local authorities, not to the manufacturer of an otherwise proper product. The designer of a PSU is not really to blame if you decide to power it with a voltage signal generated by a pathetic, home-made contraption. Your grid is the problem, start by fixing that.

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