Seasonic S12-430: Beyond the Super Tornado

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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 article 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 system 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 <250W this 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 <20 dBA/1m to over 150W output or 32° C intake temperature.

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 lower.

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.

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