You are here

Seasonic S12-430: Beyond the Super Tornado

March 17, 2005 by Mike
with Devon Cooke

  • POSTSCRIPT 1 added May 22, 2005: A fan revision
  • POSTSCRIPT 2 added Oct. 22, 2005: Corrected Efficiency Results
Seasonic S12-430 ATX Power Supply

Model SS-430HB Active PFC F3
Market Price

Seasonic is one of the PSU manufacturers which market their own products. They are both ODM and OEM, like delta Electronics, Fortron-Source, Seventeam and Enhance Electronics. This is in contrast to many PSUs that are branded by the company that markets the product, and often has little to do with either the design or the manufacturing. Seasonic is also one of the longest-lived PSU makers. Their first PSUs were made for Apple way back in the '70s. As befits a manufacturer, Seasonic adds little in the way of flashy features in their products. Virtually all the features are invisible from the outside, especially to the untrained. We have always held Seasonic products in high regard for their power delivery, efficiency and low noise; let's see if the S12-430 can meet our high expectations.

The S12 line from Seasonic has been available in the US retail market since around the beginning of February. This product line was announced late last year, and highly anticipated by the SPCR community, as the earlier Seasonic Super Tornado and Super Silencer lines were well regarded for their combination of high efficiency and low noise. The acoustic performance of the Super lines was not without controversy; they suffered through several revisions of an annoying intermittent fan control problem before finally being fully resolved in the last Revision A3. The S12 series are equipped with a 12 cm fan, from which the product name is derived. It is a replacement for the Super Tornado series, which is no longer being manufactured. Once current supplies in the retail channels are depleted, the Super Tornado will be no more.

There are five models in the S12 lineup: 330, 380, 430, 500 and 600. The naming convention is simply based on the power rating of the model. Seasonic says that the lower three models were evolved from the Super Tornado while the 500 and 600 are based on a newer circuit design. The SS-430HB under review here can be regarded as a newer, slightly more powerful version of the Super Tornado 400.

The 500 and 600 have a different model numbering sequence; SS-500HT
Active PFC and SS-600HT Active PFC rather than the HB
of the three lower powered S12s. There is a third lower power model in this
series, the SS-400HT Active PFC, which is the
model that won the first 80 Plus high efficiency PSU designation we recently
reported on.
Seasonic's main web site has details
about the full SS-xxxHT line

New packaging for the new line.

Naturally, it looks much like all the 12 cm fan PSUs. A wire grill on the
fan now, the same open exhaust grill.

The black finish is new for Seasonic, though: Flat, non-glossy.

There are a few vents on two other sides

The contents of the box: power cable, installation guide, cable management
kit, screws, 24-to-20-pin ATX adaptor, warranty sheet, and a 4-pin IDE to two
5V and a 12V fan headers.

Closeup on the adapters: The useful 3 fan headers adapter is a page from
Zalman's book.

Feature Highlights of the Seasonic S12-430
Complies with Intel ATX12V v2.0
Supports the latest
motherboards and processors.
S2FC Smart & Silent Fan Control
If it is unchanged from the Rev. A3 Super Tornado, it is about the best fan controller we've seen in a PSU. We'll see.
Active PFC environment friendly technology
Almost every Seasonic we've looked at has had it for three years; now more common.
Universal Free Input:
As in previous Super series, can be useful.
Forward Converter: Advanced design
Instead of a half-bridge rectifier, apparently.
Dual 12V
for CPU and peripherals
Specified by ATX12V v2.0
Short circuit, over voltage & over power protection Very nice.
Supports PCI Express
But no PCIe 6-pin for high power VGA
Supports Dual CPU motherboard 8-pin 12V cable
Safety / EMI Approvals: CE / TUV EN60950 / UL60950 / CSA / FCC / NEMKO Generally,
the more the better.

SPECIFICATIONS: Seasonic S12-430
AC Input
100-240V ~7A 60/60 Hz
DC Output
Maximum Output Current
Maximum Combined


Opening up the S12-430, one is greeted with an impressively large pair of unique heatsinks. The longer of the two looks much like the ones in the Super Tornado, but the smaller one is denser, with a double row of fins. They resemble teeth on a coarse comb. It's a clever design to maximize cooling fin surface area in the reduced height available to components due to the 1" depth of the 12cm fan.

Heatsinks look large and effective. (Ignore the yellow wire, which we added
for fan voltage monitoring)

A double set of teeth on this HS. As usual for Seasonic, the PCB layout is
very clean and tidy

A Yate Loon 120mm fan is used, as in the last version of the Super Tornado.

It is the medium speed version.

For the record...

The cabling on this Seasonic is twisted, like one or two other PSUs we've reviewed recently. It's said to improve EMI performance.

All the peripheral cables are twisted for improved EMI.

There are a total of seven cable sets.

  • 18" cable for main 24-pin ATX connector. Adapter to 20-pin adds 3~4 inches.
  • 18" auxiliary 12V connector
  • 19" auxiliary 4x12V connector (for dual CPU boards)
  • 33 " cable with three 4-pin IDE drive connectors and one floppy drive power connector
  • 27" cable with two 4-pin IDE drive connectors and one floppy drive power connector
  • 25" cable with two SATA drive connectors
  • 21" cable with 3-pin PSU fan speed monitor connector for motherboard

Easy-off 4-pin connector.


For a fuller understanding of ATX power supplies, please read our article Power Supply Fundamentals & Recommended Units. Those who seek source materials can find Intel's various PSU design guides, closely followed by PSU manufacturers, at Form Factors.

For a complete rundown of testing equipment and procedures, please refer to the
SPCR's Revised PSU Testing System
. It is a close simulation of a
moderate airflow mid-tower PC optimized for low noise.

In the test rig, the ambient temperature of the PSU varies proportionately with
its output load, which is exactly the way it is in a real PC
environment. But there is the added benefit of a precise high power load tester
which allows incremental load testing all the way to full power for any
non-industrial PC power supply. Both fan noise and voltage are measured at
various standard loads. It is, in general, a very demanding test, as the operating
ambient temperature of the PSU often reaches >40°C at full power.
This is impossible to achieve with an open test bench setup.

Great effort has been made to devise as realistic an operating environment for the PSU as possible, but the thermal and noise results obtained here still cannot be considered absolute. There are far too many variables in PCs and far too many possible combinations of components for any single test environment to provide infallible results. And there is always the bugaboo of sample variance. These results are akin to a resume, a few detailed photographs, and some short sound bites of someone you've never met. You'll probably get a reasonable overall representation of that person, but it is not quite the same as an extended meeting in person.

REAL SYSTEM POWER NEEDS: One very important point is that the while
our testing loads the PSU to full output (even >600W!) in order to verify
the manufacturer's claims, real desktop PCs simply do not require anywhere near
this level of power. The most pertinent range of DC output power is between
about 65W and 250W, because it is the power range where most systems will be

working most of the time. To illustrate this point, we
recently conducted system tests to measure the maximum power draw that an actual
can draw under worst-case conditions.
Our most powerful P4-3.2
Gaming rig drew ~180W DC from the power supply under full load ? well within
the capabilities of any modern power supply. Please follow the link provided
above to see the details. It is true that very elaborate systems with SLI could
draw as much as another 150W, but the total still remains well under 400W in
extrapolations of our real world measurements.

SPCR's high fidelity sound recording system was used to create MP3 sound files of this PSU. As with the setup for recording fans, the position of the mic was 3" from the exhaust vent at a 45° angle, outside the airflow turbulence area. The photo below shows the setup. All other noise sources in the room were turned off while making the sound recordings.

Ambient conditions during testing were 21°C and 17 dBA, with input of 120 VAC
/ 60 Hz measured at the AC outlet.

Seasonic S12-430 TEST RESULTS
DC Output (W)
AC Input (W)
Intake Temp (°C)
PSU Exhaust (°C)
Fan Voltage
Noise (dBA/1m)
Power Factor
NOTE: The ambient room temperature during testing
varies a few degrees from review to review. Please take this into account
when comparing PSU test data.


1. VOLTAGE REGULATION was excellent, within -/+2% on all lines in any combination of loads. The low and high voltage seen on each of the main lines is shown:

  • +12V: 12.1 to 12.3
  • +5V: 5.0 to 5.1
  • +3.3V: 3.2 to 3.3

2. EFFICIENCY was excellent. The efficiency / power output ratio curve was quite
flat. It started at a very high 79% at just 65W load and did not start to drop until 300W -- well above the
highest power draw in most systems. For most of the range in which this power
supply is likely to be used, efficiency remained between 79~83%. In this realistic power draw range of power supply is about the best we've measured.

Compared with the Super Tornado 300 and Super Silencer 400 ( Rev. A3), the reduction in power lost as heat is 4W, at best, at 200W. If we look at this number as a percentage of the heat lost, then it is about a 9% improvement at best.

3. POWER FACTOR was just about perfect across the power range.

4. FAN, FAN CONTROLLER and NOISE: The test environment is live, so
readings are higher than would be obtained in an anechoic chamber readings, due to reflections and reinforcement of sound waves off the walls, ceiling and floor.

The low start SPL of 18 dBA/1m was difficult to measure. We had to turn off everything that made any noise anywhere near the lab and wait for lulls in the traffic on Main Street two blocks away to get accurate readings. It stayed at

Overall, the fan controller showed exemplary behavior. The ramp up of the fan as load increased was very gradual. There seemed to be a significant step somewhere around the 35~36° C intake temperature point. It's where the fan began to ramp up past 6V. As with all the other Yate Loon fans we've seen so far, this one was smooth and well behaved, and even at the highest output level and temperature during the testing, it remained very modest. The recorded 33 dBA/1m is the lowest noise we have measured at 430W output -- in fact, it is the lowest noise level at full rated output for any PSU tested thus far, except for the fanless ones. At the same time, the difference between intake and exhaust temperature was always quite small, reaching the maximum of 12° C only after >20 minutes at full power load.

In actual use inside a typical modern PC, we expect this PSU to rarely ramp up even to 25 dBA/1m. Extended high loads are required for the temps to rise high enough to cause further ramping up of the fan.

MP3 Sound Recordings of Seasonic S12-430

Seasonic S12-430 @ 150W (19 dBA/1m)

Seasonic S12-430 @ 200W (22 dBA/1m)

Seasonic S12-430 @ 250W (26 dBA/1m)

Seasonic S12-430 @ 430W (33 dBA/1m)

There is some low frequency resonance noise that creeps in at >30 dBA caused by the wooden "case" in which the PSU is mounted when being tested and recorded.
Sound Recordings of PSU Comparatives

Seasonic Tornado 400 @ 65W (19 dBA/1m)

Nexus NX4090 at @150W (24 dBA/1m)

Seasonic Tornado 400 @ 200W (24 dBA/1m)


These recordings were made with a high
resolution studio quality digital recording system. The microphone was 3" from
the edge of the fan frame at a 45° angle, facing the intake side of the fan to
avoid direct wind noise. The ambient noise during all recordings was 18 dBA or

To set the volume to a realistic level (similar to the original), try playing the Nexus 92 fan reference recording and setting the volume so that it is barely audible. Then don't reset the volume and play the other sound files. Of course, tone controls or other effects should all be turned off or set to neutral. For full details on how to calibrate your sound system to get the most
valid listening comparison, please see the yellow text box entitled Listen to
the Fans
on page four of the article
SPCR's Test / Sound Lab: A Short Tour.


The S12-430 takes Seasonic a small step further along the path to higher efficiency and lower noise. It is an improvement over the Super Tornado, albeit a small one for most users, but a more significant one if you have a system with hotter, more power hungry components. While the minimal noise level is about the same as in the older ST series, the new S12-430 fan controller ramps up considerably more gradually as the power load increases. This probably has to do the incremental improvement in efficiency and more efficient heatsinks that wick the heat away just a bit faster, thus keeping the PSU a bit cooler to a higher load with less airflow. We're pretty sure that the fan controller has been tweaked to take acoustic advantage of the improved thermal characteristics of this PSU. Whatever the reasons, the noise level at higher power load is audibly improved.

Users of the Super Tornado 400 Rev. A3 should not rush out to replace it with an S12-430; the gain will be marginal unless your system is pushing the fan controller to ramp up audibly. Even then, making improvements in your overall case airflow may give you more improvement with no money outlay, and the noise level of the ST may be low enough to be masked by louder components in your system anyway.

As well as the S12-430 performed, we were a bit disappointed that it did not quite reach the 80% or better efficiency at 20%, 50% and 100% loads achieved by Seasonic's Model SS-400HT Active PFC in the 80 Plus program. (It missed at full power.) But as mentioned in the introduction, the S12-430 uses the circuit design from the Super Tornado series while the SS-400HT is a new, possibly improved circuit design. The S12-500 and S12-600, which are the retail package versions of the SS-500HT and SS-500HT, may reach such efficiency levels. We will find out soon: We have a sample of the S12-600 awaiting in the wings.

In summary, the S12-430 is the quietest fan-cooled PSU we have tested to date, by a small margin. It is also quite powerful enough for most systems, and very efficient. About the only thing more that a gamer might ask for is support for the 6-pin peripheral power connector used by power-hungry PCIe VGA cards; this feature is available in S12-430's bigger siblings, the S12-500 and the S12-600.

Our thanks to Seasonc USA for the S12-430 sample.


Seasonic made upgrades to the S12-330, S12-380 and S12-430: A new 0.24A low speed dual-ball bearing ADDA fan and aluminum electrolytic capacitors, both ostensibly for improved reliability. We put a sample of the "new and improved" S12-430 on the test bench to see whether results have changed. The results are on the next page.

* * *

Discuss this article in the SPCR Forums.

POSTSCRIPT: May 22, 2005 by Mike Chin

A news announcement posted some time in the past month at Seasonic's web site referred to several changes in their S12 line. These included two items that have an impact on the S12-430 (and lower ranked models):

120mm Double Ball Bearing Fan - The previous Yate Loon fans that came in these S12s were sleeve bearing types. Seasonic informed me that the change was made in order to reduce reject rates on the production line and in the field, and to improve consistency.

Long-lived Aluminum Electrolytic Capacitor - Apparently, higher quality Japanese aluminum electrolytic capacitors are now used for greater reliability and stable performance. More common China-made capacitors must have been used before, as is typical of most PSUs. There have been major incidents of electronics, including motherboards, affected by leaking capacitors sourced from China starting from ~2 years ago.

Both of these items are examined here in light of the potential impact on the acoustic and thermal performance of the S12-430. There is one other change that does not affect thermal performance: 20+4 Pin Main Connector - Rather than provide a 24-pin connector and a clumsy 24-to-20 pin adapter, this connector switches back and forth easily from 20 pin to 24 pin.

The "new and improved" S12-430 looks unchanged externally. Internally, the ADDA fan was the only change noted. I did see a couple of Japanese capacitors but no photo was taken.

New ADDA fan in all the S12 models. The three lower rated models get the
slow speed fan.

We could discuss the various differences between this new fan and the earlier Yate Loon fan, but it would be more expedient to go directly to PSU testing results. Yes, the new sample was strapped into the SPCR PSU test rig and put through a full round of testing.

The ambient conditions in the test lab were 21°C and 19 dBA SPL.

"New & Improved" Seasonic S12-430 TEST RESULTS
DC Output (W)
Efficiency %

(1st sample)
77 (79)
78 (82)
79 (82)
82 (83)
82 (82)
80 (79)
80 (78)
SPL, [email protected]

(1st sample)
20 (18)
20 (18)
22 (19)
25 (22)
29 (26)
32 (31)
37 (32)
NOTE: The ambient room temperature during testing varies
a few degrees from review to review. Please take this into account when
comparing PSU test data.

Only the most salient information is presented in the table above for simplicity's sake. The test data from the original sample (on the previous page) is presented in brackets.

EFFICIENCY: It's clear that that the efficiency curves of the two samples are not quite the same. The new sample starts a bit lower, catches up at about half power load, then stays at a bit higher efficiency out to max power. The difference could be attributed to the new Japanese aluminum electrolytic capacitors or to increased airflow from the new fan; it is also small enough that sample variance and tolerances within SPCR's testing procedures could be suspected. In any case, it's a negligible difference, especially in actual use. (The actually wattage differences are mostly

NOISE: The differences in SPL readings and in perceived noise are audible. At minimum speed, the new Adda fan is very nearly the equal of the earlier Yate Loon, but it remains a bit louder all the way throughout the power range. The measured difference is 2~3 dBA/1m except at the highest loads. Subjectively, the difference seems smaller than this. The Adda fan has a bit more buzz while the Yate Loon seems to have a bit more whoosh.

Between 300W and 430W, the fan in the first version barely gets any louder; the new Adda-fan version climbs a very significant +5 dBA/1m. The increased noise is comprised entirely of wind turbulence noise, which suggests that the maximum airflow of the new fan is higher than that of the older fan, and it has more cooling power in reserve at max power load. In practical terms, this discussion regarding noise at max load is not significant; even a very power hungry single VGA card system will rarely draw 250W, and as the S12-430 and its smaller variants do not offer the 6-pin PCIe connector, they will not be used for dual VGA SLI systems.

As mentioned. the Adda fan seems to have a touch more of a buzzy quality than the Yate Loon, but it is subtle and you must be very close to hear it. Beyond the low 20 dBA range, the wind turbulence noise tends to swamp over differences. Without the early Yate Loon version S12 to compare directly against, I could only say that this is "new and improved" S12-430 is one heck of a quiet PSU. If this is the cost of a little extra reliability and longevity, I doubt anyone will be aware of even paying the price.

POSTCRIPT #2: Efficiency Correction

October 22, 2005

Recently, we discovered that our power supply testing equipment and methodology were providing erroneously high efficiency results. In general, the biggest errors occurred at higher
output load points above 300W. At lower output levels, the efficiency error
was often no more than one or two percentage points. No other tested parameters were significantly affected.

Through a fairly arduous process of discovery, analysis and old fashioned problem solving, we modified our testing equipment and methodology to improve the accuracy of the efficiency results and described it all in the article SPCR's PSU Test Platform V.3. As part of this revision, we re-tested most of the power supplies on our Recommended PSU List. In most cases, the same sample was used in the second test.

The corrected and original efficiency results for all the re-tested PSUs are shown in in the article, Corrected Efficiency Results for Recommended Power Supplies. The relative efficiency of the tested power supplies has not changed.
If the tested PSUs are ranked by efficiency, the rankings remain the same whether we use the original results or the new results.

data is also being added to relevant reviews as postscripts like this one.


Target Output








Actual Output




In this case, our original efficiency calculations were 1.3~2.5% too low through to about 200W output. Above that, the original results were slightly too high, with the worst error of 4.5 percentage points off at full output power. The new figures suggest better real-life performance than before, as the all-important <200W efficiency is actually better than originally thought.


Discuss this article in the SPCR Forums.



www SPCR