A quote from SeaSonic on the S12: "The S12 Series, new for Q1 2005, conforms fully to Intel's ATX12V, Revision 2.0 PSU Design Guideline. The S12 supports the latest P4 Prescott and Athlon 64/64 FX processors, as well as PCI Express and Serial ATA. The new series adds many more features and capabilities to the existing Super Tornado line, including a new top model boasting 600W output. Up to 150W is provided on the 6-pin PCI Express Graphics output on the 500W and 600W models. The S12 takes Seasonic's industry leadership to new heights of technological superiority."

*Specifications and quote found at the SeaSonic S12 Series product page.

The power supply unit; the often overlooked backbone of your PC. Enthusiasts won't even think twice about getting the best graphics card and CPU that their money can buy. However, their power supply unit is something that is often skimped on. Hey, as long as the ratings written on the side are high enough, it's all good, right? Not necessarily, as often times, these peak voltage outputs are not accurate and the amperage behind the different output voltages is not up to the task. Fortunately, there are many good power supply makers out there who make sure that their PSUs are up to the task. One of these is SeaSonic.
The S12 arrived on the doorstep inside of good ol' brown box. Inside was the PSU itself in the retail package.



SeaSonic's S12 comes with a matte black finish. This unit won't be a distraction inside of your PC, in either the good or bad sense, leaving the rest of your components to take center stage if you have a case window installed. Sometimes minimalism is refreshing. The cables are bare like most power supplies. However, they have spun them around each other, which helps reduce electrical interference; this is a feature that is welcome for computer enthusiasts and business systems where stability is crucial.



The Molex connections on the S12 are rather interesting little devices. SeaSonic has patented their connection that is designed to, once installed, be incapable of falling out of the device, and difficult to accidentally pull out. This is useful both from a safety standpoint for a component tester. Many hardware reviewers-and even some general users- run their PCs without cases. This connector is an excellent way to stop your self from accidentally yanking something out. Props go out to SeaSonic for this connector design for these aspects. Unfortunately, the extra space makes installing some graphics cards impossible without attaching a Y adapter or a chassis fan cable due to the recessed position of the Molex on the PCB. This is a bit of an annoyance for a Radeon 9800 pro owner like my self.
Included with the S12 is a Docter Cable kit, which contains a set of Zip Ties and coil loom. There is also a 24 to 20 pin adapter for those of us who arent using BTX yet. These features are critical during this migration time going from ATX to the BTX form factor.
This Power Supply Unit is rated at 80% efficiency, meaning that 80% of the inputted power is actually usable electric current; this is a very good ratio, as many PSUs which carry higher power output ratings usually have a far lower electrical efficiency, wasting a great deal of power.
With a 120mm fan in the bottom of the unit, the S12 runs with absolute silence but still maintains good airflow thanks to the combination of this large fan and the hex grill in the back. With the increasing importance of quiet in the computing world, this is a welcome combination for those who feel that silence is golden.
The final feature of this Power Supply Unit is a 99% conversion capability Active PFC (Power Factor Correction), which makes your computer consume less power when idle than when running under load. It's a good way to reduce energy bills and simultaneously run your machine, since your PSU will only be outputting the power you will actually use.



Now that the physical aspect has been covered, let's get down to the technical details. The S12 power supply is rated at 330 watts; after I installed it in my system I was annoyed to find that it was unable to power my complete system with all fans running. However, the system did run my NF7-S, Athlon XP 3000+, ATI Radeon 9800 pro, 512 MB of DDR Ram, 80 gigabyte western digital hard drive and two case fans. It was unable to run the additional three inside my system. As power consumption goes up, you will usually want a more powerful PSU, and as such I would recommend the 400 watt version over the 330 watt. Any more is probably overkill-unless you're trying to run a server grade CPU, an FX-55, or a high end Pentium 4.
In order to test the unit, I ran the computer idle, monitoring the voltages. I then monitored the rails while running Battlefield Vietnam. The voltages, although running on a quite powerful PC for the PSUs rating, were very stable and easily within the tolerance ratings in the ATX and BTX standards.



There is no support for the legacy -5volt line, and as such strange results are given by Motherboard Monitor 5.07. However, the other voltages are relatively stable, maintaining a tolerance within 4% even in the -12 volt line. I am rather happy with these results.



The S12 is much more stable in comparison with the Super Tornado, which is a 400 watt PSU. The -12 volt line is off by 6%. While the tolerances on system components is +/-10%, the closer they are to optimal the better. The S12 makes a marked improvement over the Super Tornado. The S12 is a rock solid PSU.

SeaSonic has made significant improvements in the S12 PSU over the last model we reviewed. There is a greatly improved visual aspect, and rock solid dependability even when under heavy load. I said in the Super Tornado review that with an improved finish and other aesthetic improvements, the unit would take home our Gold award. The S12 improves on the Super Tornado in virtually every way. As a result of this, I am happy to reward the SeaSonic S12 our Gold Award and a score of 93 on our scale for making a simple, well built and powerful PSU.

• Simplistic, attractive appearance
• Doctor Cable Kit
• Very stable even under load
• Silence