Seasonic S12-500 & S12-600 Power Supplies

They are the most powerful of the S12 series, and they are based on a more efficient circuit design than the smaller models in the line. The S12-430 is the current quiet leader among fan-cooled PSUs, but the 500 and 600 have even higher efficiency and dual PCI-e vidcard support for SLI. And they all have new Adda brand 120mm fans. SPCR’s full review on the S12-500 and S12-600.

May 22, 2005 by Mike
Chin with Devon Cooke

*POSTSCRIPT added Oct. 22, 2005*

Seasonic is one of the longest-established makers of computer power supplies, and their products have consistently won respect from SPCR. The S12-430 we reviewed around two months ago turned out to be the one of most efficient fan-cooled PSU encountered, and also the quietest by a pretty big margin. Early production samples of the highest powered models in the S12 line, the 500 and 600, were also on hand at the time of the review, but Seasonic requested that we delay the review until newer samples were made available. A production change in the fan was coming, and this would affect the entire S12 line.

The Seasonic S12-500 and S12-600 differ from the lower powered S12 models more than just by power rating. These models actually use a different circuit design than the lower power models. Their model number, SS-500/600HT Active PFC F3, is different from the rest of the S12 line, SS-330/380/430HB Active PFC F3. The latter models feature upgraded variants of the circuit design used in the now-discontinued Super Tornado, while the 500 and 600 are entirely new. There is a third model, SS-400HT Active PFC F3, that logically belongs with the S12-500 and S12-600, but for whatever reasons, it appears to be unavailable for the retail market at this time.

80 PLUS APPROVED

The SS-xxxHT Active PFC F3 models have all been 80 PLUS certified.
Regular readers of SPCR (and dedicated observers of the power supply scene) will know about 80 PLUS. SPCR provided news coverage about this initiative to promote the use of efficient power supplies in computers. There was also related discussion on page three of the article, A New Energy Star.

80 PLUS is described as “a national buy-down program for desktop computers and desktop-derived servers that contain highly efficient power supplies.” The program invites submissions of PSUs, which are tested, and if the units pass, they become 80 PLUS approved. The test is quite tough: It calls for 80% or better efficiency at 20%, 50% and 100% of a PSU’s rated power output. When a system integrator uses any 80 PLUS certified PSUs in systems, they can receive rebates through the 80 PLUS program, ostensibly to offset the initial higher cost of these highly efficient PSUs. You can check out all the details of the program, administered by Ecos Consulting, a company that “only undertakes projects that make a positive environmental impact”, at the 80 PLUS web site.

The Seasonic SS-400HT APFC F3 was the first PSU to be approved by the 80 PLUS program. There are now four Seasonic PSU models on the approved products list. At time of posting, three other brands each feature a model on the an 80 PLUS approved PSU list.

What all this means to the end user is that the S12-500 and S12-600 should be >80% efficient at all power loads above 100W and 125W respectively. In SPCR’s test rig, the S12-430 achieved the requisite >80% efficiency between 90W and 250W load but fell shy of it at maximum load. The 500 and 600 shouild fare better.

NEW IMPROVMENTS

The retail boxes for the 500 and 600 have new sticker labels that suggest changes and improvements.

New stickers on the box.

The blue orca image is now flanked by two prominent labels on the top left corner:

Two new labels on the S12-500 and S12-600 box.

It turns out that the top larger sticker applies to all of the S12 line:

120mm Double Ball Bearing Fan – It’s not clear exactly what type of ball bearing was used in the previous Yate Loon model fans that came in these S12s, but it must have been different for this point to be made. Seasonic states that the change was made in order to reduce rejects on the production line and to improve consistency.

Long-lived Aluminum Electrolytic Capacitor – Apparently, higher quality Japanese aluminum electrolytic capacitors are 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 incidents of motherboard and PSU brands being affected by leaking capcitors sourced from China starting from ~2 years ago.

The second smaller sticker applies only to the S12-500/600:

Support SLI – PCI-Express X2 – Two 6-pin connectors with sufficient current capacity for PCI-E & SLI systems are provided. This is to ensure gamers get all the bang they need. Only the 500 and 600 are so equipped because they’re the models deemed to be high enough power capacity to handle SLI.

A news release detailing these improvements can be found at Seasonic’s web site.

The PSUs themselves do not appear much different than the early samples or the S12-430 except for the dual 6-pin PCIe connectors and a few subtleties. The contents of the box are also the same.

Clockwise, from top left: S12-600, box, Dr. Cable kit, instruction
booklet, mounting screws, Seasonic sticker, 4-pin Molex to 3 fan headers adapter,
AC cable.

There are a few vents on two other sides

Here’s where some differences show up: The S12-600 (and 500) on the left has smaller and fewer vents all around compared to the S12-430 on the right, and the output cables are positioned so that they exit on the side closest to the motherboard when installed in a typical ATX case. Most users would say this cable positioning is better for cable management.

For the record, here’s the label from the S12-500. The one on the 600 is
identical except for the particulars.

Note that the combined maximum power rating is the only significant difference between the the 500 and 600 models. The individual rail differences are almost insignificant ? just 36W more for the 12V lines. It may be interesting to closely examine the output specs for the S12-430. Here, the 12V lines are significantly lower, but while the +3.3 and +5V individual lines are the same 30A as in the bigger models, the combined maximum for those lines is significantly lower too.

PHYSICAL DETAILS

Opening up the either the S12-600 or S12-500, one is greeted with an impressively large pair of unique heatsinks. They are both dense and quite large, with a double row of fins. They resemble teeth on a coarse comb. The basic design originated in the Super Tornado; it is a clever way to maximize cooling surface area in the reduced height available to components due to the 1″ depth of the 12cm fan.

Big HS fins reminiscent of teeth on a coarse comb.

Side view show components tucked under HS fins.

The other side is where the cables are terminated.

This 7-blade medium-speed ADDA fan has replaced a 5-blade Yate Loon 120mm
fan used in earlier versions of the S12-500 & 600.

As with the S12-430, cabling on the 500 and 600 is twisted to minimize EMI.

All the output cables are twisted for reduced EMI.

There are a total of nine cable sets. The main ATX cable seems a bit on the short side at 16″, but it should reach most motherboards in most cases.

• 16″ cable for main 20+4 pin ATX connector.
• 26″ cable with two 6-pin PCIe video / SLI connectors
• 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
• 2 x 24″ cables with two SATA drive connectors each
• 21″ cable with 3-pin PSU fan speed monitor connector for motherboard

Easy-off 4-pin connector.

TEST RESULTS

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 18 dBA, with input of 120 VAC
/ 60 Hz measured at the AC outlet.

The results of the testing were so close between the two samples that they might as well have been identical. The differences were typically within 1%. Rather than clutter up the article with two complex charts that have the same data, the two sets were combined. The worse of the results obtained for the two samples are presented here. Naturally, only the S12-600 was tested at 600W.

ANALYSIS

1. VOLTAGE REGULATION was excellent, within -/+2% on all lines at all test loads, except for the 3.17V reading at full powerful, which was -4% off. The low and high voltage seen on each of the main lines is shown below. Unless otherwise noted, the lowest voltage recorded were at the highest loads.

• +12V: 11.91 to 12.12
• +5V: 4.90 to 5.02
• +3.3V: 3.17 to 3.32

2. EFFICIENCY was excellent, as expected of these 80 PLUS certified power supplies. The efficiency / power output ratio curve was quite
flat from below 20% of rated load all the up close to maximum power. The flat 87% efficiency obtained from 200W to 400W is most impressive. In practical applications, these PSUs will be very tough to beat for energy efficiency, with their combination of high AC/DC conversion efficiency and active PFC.

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

4. TEMPERATURE: The high efficiency combined with the large heatsinks and effective airflow in these PSUs to provide the best in / out air temperature rise recorded in our PSU tests. At all power loads of 250W or lower, the temperature rise was only +3°C. It gradually rose to +7°C at full power load. This compares very favorably with many PSUs that hit +7~10°C in / out temperature rise by 50% load. It is not unusual for 15°C to be exceeded at full power loads. This means that the S12-500 and S12-600 are very effectively cooled and overheating should rarely be a cause for concern.

5. 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 start SPL of 21 dBA/1m was 3 dBA higher than that measured on the original version of the fan-cooled PSU champion (for noise), the S12-430. But it was still extremely quiet. The new Adda-fan equipped 430 is only one decibel quieter. (See postcript to S12-430 eview.) The first hint of fan noise increase was heard (and measured) at 150W output or ~31°C intake temperature. The overall noise stayed quite modest until past the 250W load. When listened up close. the dual ball bearing fan has a bit of the typical ball-bearing chatter, but it is very subdued, and based on our recollection, much quieter than the earlier 5-blade Yate Loon fans first used in these models.

Like the S12-430, the fan controller in these high power PSUs showed exemplary behavior. The ramp up of the fan as load increased was gradual. Compared to the S12-430, the overall noise level was typically 2-3 dBA louder through much of the power range. As the power load went past 300W and the fan voltage climbed beyond ~8V, the higher capacity of the medium speed in the 500 / 600 began to make a bigger difference ? in airflow and the resulting turbulence noise. For those who have a need for such high power capability as offered by the S12-500 and 600, the increased noise at high power is a modest price to pay, especially when acoustics at typical power loads (<300W, even for high power gaming rigs) is so well behaved.

In actual use inside a typical modern PC, we expect these PSUs to rarely ramp up beyond ~30 dBA/1m. Extended high loads are required for the temps to rise high enough to cause further ramping up of the fan.

CONCLUSIONS

The new and improved S12-500 / 600 power supplies find Seasonic at the top of their game. These high power models pick up where the S12-430 leaves off and continue on quietly, steadily delivering power on demand. Tops for efficiency, for low noise, for stable high power delivery, and for the minimalist approach that strikes a chord of quality for many users.

Our own testing confirmed that the 500 and 600 do indeed reach 80% and better efficiency at 20%, 50% and 100% loads demanded for the 80 Plus program, which has certified both models. The 80 PLUS test results are available as downloadable PDF files and worth a careful examination. So far, Seasonic appears to be the only PSU brand with a retail presence to have achieved 80 PLUS approval.

While they do not plumb the quiet depths the way the original S12-430 did, the 500 and 600 are nearly as quiet at low to medium load and can take on any PSU of similar power capacity without any acoustic handicap. In fact, the reverse is true: There is not a single PSU we know of that can produce so much stable power as the S12-600 and stay as quiet. At the more likely loads of <250W, the noise level stays well in the mid-20s (in [email protected]), which is competitive with the majority of quiet PSUs.

We wrote at the end of the original S12-430 review that about the only thing more a gamer might ask for is support for the 6-pin power connector used by power-hungry PCIe VGA cards. Two such connectors are now available in the S12-500 and the S12-600. If you seek quiet, stable, high power without flash, look no further than the S12-500 and the S12-600.

Our thanks to Seasonic USA for the S12 samples.

NOTE: A postscript has been added to the Seasonic S12-430 review to investigate the effects of the change to the Adda fan.

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