There is no doubt the S12 series power supply units have managed to launch Seasonic to the top of many enthusiast's hardware lists.  But just because you purchased an S12 power supply doesn't mean it is the cat's meow.  Seasonic offers a wide range of S12 series power supply units ranging from the extremely powerful and expensive S12-600 600W to the more modest S12-330 with a total power output of  (you guessed it) 330 watts.  Today, HardwareLogic will examine the smallest and most inexpensive power supply from the S12 series, the 330W SS-330HB and determine if this little gem is exactly what you need for your system or if you should be looking elsewhere for your next PSU purchase.

Seasonic Feature	Comment
Multiple +12V Outputs for enhanced +12V current capability to broaden utilization possibilities	This feature is part of the ATX 12V 2.0 standard and pretty common on most any new power supply on the market today.
Super High Efficiency (up to 80%).  Optimal solution for lower energy Consumption, noise, and heat.	Higher efficiency is definately better and 80% is decent.
Forward converter circuit design.  Advanced design for high reliability and efficiency.	A DC to DC converter technology with better reliability and efficiency compared to the half-bridge design.  Read more here...
High reliable aluminum electrolytic capacitors provide top quality components increase product life and reliability	Obviously using higher quality components is a good thing.
Active power factor correction (99% PF) reduces line loss and power distortion.	It's always nice to see Active Power Factor Correction implemented, as it helps remove the "ripples" in the power being delivered.
Universal AC Input (full range).  Plug and run safely anywhere in the world.	Also a fairly standard feature.
Smart & silent fan control (S�FC).  Smart thermal control to balance noise and cooling.	The fan is thermally controlled so it will only spin faster when the unit gets hotter.
Soft mounting rubber cushions reduce fan rotation and vibration noise.	Another very nice feature you (unfortunately) don't see on very many power supply units.
12cm ball bearing cooling fan increases airflow and lifetime and reduces rotation speed and noise.	The larger fans move more air and are quieter, definately a good thing.
Ultra ventillation (hone comb structure) doubles the airflow and lifespan with half the RPM and noise.	Pretty lofty claims for a stamped exhaust vent.  But this design does offer less restriction compared to the simple circular mesh.
PCI-Express connector supports new PCI-E video cards.	High end PCI-Express video cards require an extra power connector and this PSU natively supports this 6-pin 12v power connector.
All in one DC cabling design supports PC, IPC, workstation, server, & dual CPU systems (*applies to models 430W and above).	Apparently the 330W we are testing here today is not cool enough for this...
Patented easy swap connector allows you to unplug the connectors easily and quickly.	These things are GREAT!
3 year warranty shows our commitments to superior quality.	As you would imagine, the longer the warranty the better.

Looking at the specification sticker on the side of the power supply unit, we find the following:

DC Output:	+3.3v	+5V	+12V1	+12V2	-12V	+5Vsb
	20A	20A	8A	14A	0.8A	2A
	120W		264W		9.6W	10W
	Total Power:				330W

Also visible on the specification sticker is the proudly displayed RoHS compliance logo, meaning that the solder and components used in the power supply meet the standards put in place by European countries to be more environmentally friendly.

Seasonic Packages the S12-330W PSU in a typical cardboard box adorned with colorful images and the features and specifications of the unit contained inside.

Packaged with the S12-330W we find the typical power cord, bag of screws, printed user manual, and warranty card.  Not so typical is the "Powered by Seasonic" case sticker and molex to dual floppy power adapter.  Personally, I like the fact that Seasonic has chosen to completely remove the floppy power connectors from the native power supply cable leads as these connections are very rarely (if at all) even used anymore.  This makes room for more widely used connections, like SATA power.

As the name implies, one of the more signifigant attributes of this power supply is its silent 120mm intake cooling fan.  I can honestly say that when Seasonic says silent, they come pretty darn close to it.  This is probably the quietest power supply I have ever heard (or NOT heard! - Ed. Note).  Even with my ear so close to the fan that my hair gets clipped by the spinning blades, I can't make out a definite motor bearing noise and there is absolutely no noise of air movement.  But this silence does come at a cost; airflow.  Fortunately, being a 330W power supply, there isn't a whole lot of heat produced by the unit so cooling doesn't need to be extremely beefy.  In fact, during testing, the exhaust air coming out the rear or even the unit itself never even got warm.  So not only is this power supply incredibly quiet (virtually silent), it is still able to keep the components on the inside of the PSU cool.  Just don't count on this PSU to move a lot of extra air out from inside your case because the airflow is minimal.

In order to make the low airflow of the cooling fan feasible, the exhaust needs to be just as efficient.  Here we see the honeycomb design of the exhaust vent which maximizes open area for very low resistance and better airflow characteristics compared to simple circular patterns.  On this rear exhaust vent we also find the power switch and power plug.

At the rear of the PSU is where we find all of the cables available on the S12-330W.  Every cable comes from the factory fully sleeved with black heatshrink and sleeving.  Most power supply manufacturers only sleeve small portions of the cables or don't even bother with any sleeving, so it's very nice to see Seasonic make the effort to sleeve the entire length of every cable!

Another nice thing I want to point out here are the patented "Easy Swap" molext connectors.  Those two little tabs on the top and bottom of each molex power connector are squeezed together when you are removing the connector from a device and they press down and forward helping the molex connector push away from the device it is plugged into.  It might look flimsy or gimmicky, but I assure you that I very much enjoy such innovations as they really do make it much easier to remove the plugs.

Recently revised on the 330W S12 power supply is the addition of more SATA power connections and the 6-pin PCI-Express power cable.  Both are welcome additions and I cannot find any reason to complain about any of the connections available on this unit.

Connector Type	Count
20+4 pin ATX power	1
4-pin ATX 12V CPU power	1
6-pin PCI-Express power	1
SATA power	4
4-pin Molex	6

Category	Component	Notes
Processor	AMD Athlon 64 3200 Venice	Overclocked to 210mhz x 10 (2.1Ghz) on 1.4v
Motherboard	Chaintech VNF4 Ultra	Chaintech V5.0 BIOS
RAM	OCZ Platinum PC-4800 2x512MB	210mz 1:1 with 7-2-2-2 and 1T timings (2.9v)
Video Card	eVGA 6600GT 128MB PCI-Express x16	Stock 500mhz core and 1.0Ghz memory speed 8x AA, 16x AF, and "High Quality"
HDDs	Western Digital 74GB Raptor Seagate 250GB 7200.8	SATA, 10,000rpm, 8MB cache  SATA, 7200rpm, 8MB cache
Power Supply	Seasonic S12-330W
CPU Cooling	Thermalright XP-90	Arctic Sliver 5 TIM and 92mm Panaflo Ultra Quiet FBA09A12L1BX
Other	LiteOn DVD-ROM LiteOn 52x CD-RW USB 2.0 42-in-1 card reader 2x120mm Evercool fans	Full speed (12v)

All testing was done using the components listed above installed together with Windows XP Professional SP1.  Measurements were taken using a digital multimeter and the lowest recorded measurement was used in the final charts.

Here we see slightly low 12v rail measurements, but all still within a 2% variation and acceptable according to standard ATX power supply requirements, which allow a 5% variance.  The measurements taken from the main 24-pin ATX power connector on the motherboard are significant because this is also what's powering the video card and RAM.

Measurements taken from the molex connectors show similar results to what was found on the main 24-pin ATX power connector - a little low, but still within acceptable range (less than 2%).

Looking at the 4-pin ATX 12v power connector that plugs into the motherboard to supply the CPU with extra power, we find that this too, is a little low.

Finally, the same can be said for the PCI-express power connector.  Even though this connector was not in use in the test system, voltage measurements from it show that this connection was still recieving fairly stable power, but still slightly on the low side.

These results suprised me a little.  I was fully expecting a quality 330W power supply unit from Seasonic to be able to handle my test system, but I found that the 12v rail was consistantly low.  While the rails barely fluxuated within the single tests, the 12v rail jumped up and down a little between the tests depending on how much load was placed on the system.

Warranty and Support

Even from the first time I checked out Seasonic's website, it was obvious that they are very customer focused.  This particular PSU offers a commendable 3 year warranty, which seems to be the standard for most all of Seasonic's power supply units.  Seasonic also has a nice list of Frequently Asked Questions available under Technical Support.  If you still cannot find the answer to your question in the FAQ's or need help regarding warranty information and support, you can contact Seasonic by means of telephone, post mail, or e-mail.  They even have office hours Monday ~ Friday 9am-12am / 1pm-5pm except holidays.

Conclusion

Criterion	Score	Comments
Featureset	9/10	The S12-330W is more of a budget oriented product, but includes features often found only on more expensive, higher end units.
Cables and Connections	19/20	Seeing an entry level PSU come fully sleeved from the factory is a big plus.  Throw in the fact that it still includes many SATA and molex power connections as well as a PCI-Express connector, I have to say I am very satisfied with the cables and connector selection on the S12-330W.  The only thing missing is an 8-pin EPS connector.
Power	15/20	At 330W, this unit is not extremely powerful, but the price is right and is meant for a low-end or mid-range system build.  More importantly is the amperage on each voltage rail, and while the 3.3v and 5v rails are sufficiently powerful, I would liked to have seen a little more amps on the 12v1 rail.
Performance	18/20	This is only a 330W power supply unit, so we can't expect it to power a multi-GPU watercooled system, but I feel that the test system used was very fair and of a typical configuration most likely to be used with the S12-330W.  Although 12v power was a little less than desireable, I never experienced any instability during my several weeks using this power supply, even running for several days straight at 100% CPU load.
Cooling and Noise	10/10	The S12-330W is honestly one of the quietest (if not the quietest) PSU I have ever used.  In addition to being whisper quiet, I never noticed any part of it overheat or even get hot.
Warranty and Support	9/10	With a three year warranty and a website with lots of great information, Seasonic deserves a fairly high mark for warranty and support.
Price/Value	7/10	Currently available for about $60, the S12-330W is very fairly and competitively priced.

Final Thoughts

All in all, I am left with mixed feelings about the Seasonic S12-330W power supply unit.  On one hand it is incredibly quiet, has nicely sleeved cables with a nice selection of connections for a 330W power supply, and has a good list of features.  But on the other hand I found it to be somewhat weak, even compared to Seasonic's very own

"Super Versatile" 250W power supply unit.  I couldn't expect a 330W PSU to power an enthusiast rig, but to be perfectly honest, I was expecting slightly better results than what I measured, especially powering a fairly "modest" system like what was used for testing.

There are not a lot of quality 330 watt power supplies out there with features like active PFC and split 12v rails with whisper quiet operation, so already the S12-330W is in a league of it's own.  Given this, I think it is a very good product, but as far as <400W power supplies go, there may be better (more powerful) alternatives depending on your system build.

Other Reviews of Note

Its always nice to have more than one opinion on a component before you spend your hard earned money. For one, We may see something others missed, or vice versa. As with all reviews published at HardwareLogic, we'll not only give you our recommendation, but also point out some reviews from some other great sites around the web.
Phoronix
MadShrimps
Silent PC Review
ModSynergy