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Seasonic "S12" 430w PSU Review

By: Mike Wright | Other PSUs in Cases, Cooling & PSU | Posted: Jun 6, 2005 4:00 am
TweakTown Rating: 9.0%Manufacturer: Seasonic USA



When it comes to testing a power supply, there are a lot of choices in how to tackle the job. I have found that while a multimeter can give scads of data, most of us don't have a clue what all these facts and figures mean. Even the elite of the enthusiast crowd doesn't always keep up with the inner workings of a power supply. So what do we do?


Since a majority of our readers tend to fall into the enthusiast realm, why not run the power supply in an Athlon64 based system and then stress it out? After we get things worked up nicely by running 3DMark loops and burning CD disks, we'll take a reading of the power levels right in the middle of this mess. This ought to give us a workable answer as to whether or not this product can give us the power we need under stressful conditions. If it can give solid results under this type of operating condition, it will let us know that it can handle the regular chores that we are likely to throw at it.


So lets start off with a look at the test rig:


EPoX 9NDA3+ Motherboard - nForce3 chipset (Supplied by EPoX)


Athlon64 FX-53 @ 2.4GHz (Supplied by


Swiftech H2O-120 water cooling (Supplied by Swiftech)


2x 256MB OCZ PC3500 DDR (Supplied by OCZ)


Sapphire X800 XT PE (Supplied by Sapphire)


SoundBlaster Live


D-Link 10/100 NIC


52x CD-ROM




Western Digital 80GB 8MB SATA Hard Drive


Seagate 40GB 2MB Hard Drive


Sony 3.5" Floppy Drive


2x 80mm case fans


2x 120mm case fan


All right then, the processor is running at 1.55v, the memory is at 2.8v and the AGP is at default. The system is a powerhouse and the video card is known to cause weaker power supplies to cringe in terror. Add the stress factors mentioned above and we should get a fair look at what this PSU is capable of.


As a final note, most manufacturers claim a leeway of +/- 5% of any given output level. Using this as a common ground, we should end up with rail voltage levels of 3.135-3.465v on the 3.3v rail, 4.75-5.25v on the 5v rail and 11.4-12.6v on the 12v rail. Keep this in mind when we go through the numbers below. Higher values can be beneficial, lower values bear watching.


I went ahead and tested the Seasonic PSU against some top contenders in the enthusiast market so we would have a legitimate comparison. The Antec and Thermaltake units I used for the comparison are very solid performers in their own right, so if the Seasonic can keep up with these, it will make a solid statement.



After the smoke cleared and the dust settled, the Seasonic didn't do too badly at all. While it didn't manage to take top honors, it was able to perform in a very acceptable manner when the system was stressed. For those who are using the Socket 939 platform and are concerned about compatibility, I noted no problems at all when running the test system.


As far as steady power levels across the rails, the 12v and 3.3v rails gave very consistent results. The 5v rail, however, showed a small amount of fluctuation, bouncing from 4.94v to 4.97v at different intervals. While not enough of an issue to cause any likely problems, it at least bears noting the issue since it came up during our testing.


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