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Seasonic Super Silencer 400 - ATX12V 1.3

July 16, 2003 -- by Mike Chin

Product Seasonic Super Silencer 400 PSU (ATX12V v1.3 compliant)

Model SS-400AGX Active PFC rev 1.1
Manufacturer Sea Sonic Electronics
Supplier Sea Sonic Electronics
USA
Price US$99

Readers who have scoured the SPCR power supply section will know that the Seasonic SS-300FS-APFC was our first unsolicited review sample. It was just after Seasonic's entry to the US retail market. Beneath its plain Jane exterior, the SS300-APFC turned out to be a functional beauty, with excellent efficiency and a highly intelligent thermal fan speed control circuit (S2FC) that remains the one to beat even today, a year and 12 PSU reviews later. The 300 went on our Recommended PSU list, of course (as did the 400W version of the same, the non-PFC 300W and the 200W SFX version as well; they all feature the same excellent S2FC fan controller.)

Seasonic's engineering and marketing teams have not been idle. An e-mail press release about a new line of Super Silencer and Super Tornado PSUs came in a couple of weeks ago, along with an invitation to review these new models, which was naturally accepted. Not much later, UPS delivered a carton of samples.

The Super Silencer line is the next generation of the SS-xxxFS-APFC line we're familiar with. The Super Tornado is a 120mm fan PSU of the type first seen with the Fortron brand, which has become quite popular with SPCR forum members.

This review focuses on the Super Silencer 400; there are 3 others in the line: A 300W, a 350W and a 460W model. Apparently, there will be a period of transition during which the SS-xxxFS-APFC line coexists with the "Super" line. In some markets, the Super series may not be introduced for some time. It has been available in Taiwan since some time in June and also in Japan since the beginning of July.
In the US, Seasonic's "Super" line will be available very soon at Fry's Electronics.

Silicon Acoustics

also sells Seasonic "Super" PSUs

NEW PACKAGING

While the SS-xxxFS-APFC generation PSUs featured a pleasant box, it was hardly an example of hard-hitting modern retail packaging. It is evident from a single glance at the new packaging that Seasonic marketing have done their homework. The Super Silencer box is designed to grab your attention and sell you on its features as you ponder your purchase in the store. (There's enough reading material on the box to last a quick lone geek lunch!) Actually, the box is good enough to explain most of the features: All the images in this section come from the box.

Aside from the 400W designation, the main cover photo immediately tells you that this model features a proper wire grill and automatic universal AC input voltage. Then there are the phrases "Ultra Quiet" and "Energy Saving" (One wants to ask why throw ultra into the mix when super is already in the name?!)... and 7 icons that include the text:

1) 80% Efficiency. In PSUs, this specification refers to how much power is lost when converting AC voltage to DC voltage. A voltage and power output level is usually specified. In a separate e-mail, a Seasonic engineer informed me that the 80% efficiency rating is for 240V, at full power. The rating for 120V is 78%; it is almost always lower for the 120VAC input. Regardless, these are the highest efficiency numbers I have seen claimed for any PSU meant for a PC. The most common number seen is 65%, with 70% being the "standard" number claimed for more high-end PSUs.

2) Active PFC - 99%. The high AC/DC conversion efficiency is combined with Active Power Factor Correction for a PF of 0.99. This results in extremely low energy waste, as explained in detail on the back of the box.

3) Free Input. This refers to automatic AC input circuitry which allows the unit to run without manual switching at any AC voltage from 100V to 240V.

4) S2FC - 25 dBA. It's the fan control circuit from Seasonic's existing PSU series, and they're claiming a noise level of 25 dBA, although no distance or power level is cited anywhere. The S2FC circuit was described in detail in the review of the SS-300-APFC. In essence, it keeps a relatively powerful fan running at extremely low speed until and unless a fairly high load and temperature is reached. After that point, the rate of fan speed change follows an exponential curve so that the maximum RPM / airflow is saved for the highest load. In this way, the PSU runs very quietly under normal and even fairly demanding loads, yet has the full cooling power of the fan when it is needed.

5) Cushion Fan. Rubber grommets are used on the 4 fan mounting screws to reduce noise by lowering the amount of vibration transmitted from the fan to the PSU and through it, to the PC case. Grommets and screws are not as effective as mounts made completely of rubber or other elastomers, however. The grommets are not visible from the outside.

6) Forward Converter. This is a reference to more advanced circuitry that replaces the usual bridge rectifier circuit. I was told it is part of what makes the high 78% / 80% efficiency possible.

7) Doctor Cable. It's a cable management kit consisting of a spiral cable cover made of translucent soft plastic, a handful of zap-straps (locking cable ties) and a large cable mount. The image below from one of the box side panels tells the story. The parts themselves are commonplace in electronics parts stores, but its inclusion in the PSU package is unique. It's practical, generous and well thought out. It makes you wonder why all retail PSUs don't come with something similar!

Warranty coverage is provided for a period of 3 years, which is very generous. Seasonic has implemented an on-line RMA system to expedite service if and when it becomes necessary. The warranty card refers to http://www.seasonic.com.tw/usa/index.jsp. Full details of the warranty can be seen there.

PHYSICAL DETAILS

The sample came with the usual power cord, 4 mounting screws, a multi-page manual, a warranty card, and the "Dr. Cable" cable management kit.

There is nothing particularly unusual in the appearance of the Seasonic Super Silencer 400.

The photo below shows the PSU from behind, upside down. All the intake air vents are visible. Note the absence of any vents on the panel that would be facing the CPU in a tower case. This is normally done to ensure that all the intake air from flows completely across the internal heatsinks. The ones on the back seem a bit restrictive. The unvented gap in the middle covers the space between the 2 internal heatsinks; it seems that the intake slots are placed in such a way as to direct the air over specific components in the PSU. A large coil lies on the other side of the 3 slots on the side.

You might notice in the photo above that the output cables are located in what would be the bottom corner of the PSU when mounted in a typical tower case. The cable exit location maximizes the reach of the cables.

Cables & Connectors - There are 7 wire sets. The longest cables are long enough to reach just about anywhere even in a full tower case, and 8 Molex 4-pin connectors are probably enough for fully loaded PCs. Serial ATA power connectors or adapter are not provided.

2 cables, 33" long, each with three 4-pin IDE drive connectors and 1 floppy drive connector

1 cable, 19" long, with two 4-pin IDE drive connectors

1 cable, 19" long, with main 20-pin ATX connector
1 cable, 23" long, for 12V (P4) connector
1 cable, 23" long, for 3.3V connector

1 cable, 23" long, for PSU fan RPM monitoring (3-pin motherboard header)

Opening the cover exposes generous sized but not massive heatsinks, and a clean, uncluttered layout similar to that in the previously reviewed SS-300-FC-APFC. (I could not help noticing the very tight fit of the PSU cover when it was put back on; it is better than in the previous Seasonic models, and better than the norm for PSUs in general.)

There seems to be only one large capacitor, presumably for the output. It seems a bit small considering the rated capacity of this PSU, but then I am no PSU engineer.


NOTE from a Seasonic PSU Engineer: (after this review was posted)

The reason why a single capacitor is used instead of 2 is that the full range Active PFC circuit needs 380VDC for energy storage (bulk capacitor), and the manual switch model (non PFC) needs only half of the voltage. You find generally that non-PFC models have 2 bulk CAPs (200~220Vdc xxx uF ~xxx depends on wattage) and Active PFC models have 1 bulk CAP (400~450Vdc xxx uF ~xxx depends on wattage).

How many CAPs are used does not matter much electronically if the total uF is the same. Most manufacturer choose 2 CAPs (200Vdc XuF) instead of 1 CAP (200Vdc 2*XuF) because of lower cost. In our situation 1 CAP (400Vdc xxx uF) was cheaper than 2 CAP (400Vdc xxx/2 uF). Other full range circuit design with 1 CAP (400Vdc xxxuF) include monitors, OA machine, adapter.....


The fan has a 3-pin connector to the main printed circuit board. The detail of this connector and the RPM output lead for the motherboard header are shown below.

One unusual aspect of the fan circuitry is that the ground is isolated from the rest of the PSU. Apparently this ensures that the fan voltage does not sag even with high loads on the main output lines. Normally, only the positive voltage lead to the fan needs to be tapped; the negative voltage can be read from any black lead on any output connector, a 4-pin Molex being the most convenient. Not so in the Super Silencer 400. Both + and - leads to the fan had to be tapped to measure the fan voltage.

The fan itself is a "SuperRed" 80mm ball bearing model CHA8012CB-A rated for 12VDC and 0.17A current made in China by Cheng Home Electronics Co Ltd. This is not a brand encountered by SPCR before. The company is based in Taiwan, according to their website. Seasonic says this fan has a minimum airflow rating in free air of 34 CFM and a noise level of

SPECIFICATIONS

The Seasonic Super Silencer 400 is the first PSU we've seen that is compliant with Intel's ATX12V Version 1.3 Power Supply Design Guide released a couple months ago. One of the changes from version 1.2 to 1.3 is the removal of the –5V rail. It is no longer required, and the Super Silencer family does not provide it. Apparently its absence does not cause any conflict with recent motherboards produced prior to the v1.3 guide.

The technical specifications provided in the manual and brochures are rather skimpy.* No peak currents are given, for example, nor voltage regulation tolerances. Note, the high 22A rating for the 12V line.

AC Input
AC Input 100-240V ~7A 50/60 Hz
VDC Lines
+3.3V
+5V
+12V
-12V
+5VSB
Max Current
28A
30A
22A
0.8A
2A
Max Output
180W
-
Peak Output
450W
Total Output
400W

*ERRATA: After this review was posted, a Seasonic technical representative pointed out that the original 32A cited for the +12V line above was incorrect; it has been changed to the correct 22A. Also a complete specification document in PDF format was forwarded, which does contain very detailed technical data. This data includes the following:

VDC Lines
+3.3V
+5V
+12V
-12V
+5VSB
Voltage Regulation
±5%
±5%
±5%
±10%
±5%
Peak Current*
-
-
24A
-
2.5A

*minimum 1 second


4-in-1 Protection: Over voltage / over power / over temperature / short circuit protection. One presumes all of these conditions will cause the PSU to shut itself down.

Operating Temperature: 0 to 50° C. Relative humidity: 20% to 80%. The rated power will reduce from 100% to 80% from 40° C to 50° C linearly.

MTBF (mean time between failure): Typically over 100,000 hours at 25° C under full load, excluding the DC fan.

There are 13 logos for safety and EMC approvals:

TEST METHODOLOGY

Parameters Tools
DC load on PSU DBS-2100 PSU load tester
Ambient temperature
Any number of thermometers
DC voltage regulation
Heath / Zenith SM-2320 multimeter
AC power
Kill-A-Watt Power Meter
The core PSU test tool on SilentPCReview's test bench is the DBS-2100 load tester, made specifically for testing computer power supplies. The machine consists of a large bank of high power precision resistors along with an extensive selection of switches on the front panel calibrated in Amps (current) and grouped into the 5 voltage lines: +5, +12, -12V, +3.3, +5SR. Leads from the PSU connect into the front panel.

The DC output connector closest to the PSU on each set of leads is used for hookup to ensure that the current is distributed through as many short leads as possible. The wires get very hot when pushing a PSU to high output.

The Seasonic Super Silencer was tested at 5 DC output power levels:

65W: A very typical DC power draw by many system at low / modest load.
90W: Established previously as a typical max power draw of a midrange desktop PC.
150W: For higher power machines.
300W: Perhaps a typical peak demand on real systems
400W: Full rated power.

Care was taken to ensure that the load on each of the voltage lines does not exceed the ratings for the PSU. The PSU was left running 10 minutes at each power level before measurements are recorded.

The DBS-2100 is equipped with 4 exhaust fans on the back panel. A bypass switch toggles the fans on / off so that noise measurements can be made. The resistors get very hot under high loads.

Kill-A-Watt AC Power Meter is plugged into an AC outlet on the side of the DBS-2100 in the above picture. The AC power draw of the PSU is measured at each of the 4 power loads. The Kill-A-Watt is used to measure:

Efficiency (in AC-to-DC conversion) at each power level. This is the efficiency figure provided by PSU makers, obtained by dividing the DC power output (as set on DBS-2100 load) by the AC power consumption. Efficiency varies with load, and also temperature. The main advantage of high efficiency is that less power is wasted as heat. This means a cooler PSU that requires less airflow to maintain safe operating temps (read: quieter).

Power Factor (PF). Read directly off the Kill-A-Watt. In simple terms, it tell us how much AC power is lost to harmonics (unnecessary electromagnetic energy) while driving the PSU. In practical technical terms, it is the difference between the V(oltage) x A(mperes) and AC power in Watts measured by Kill-A-Watt.

PF varies somewhat with load. The ideal PF is 1.0, which means no AC power is lost. A PF of 0.5 means that to deliver 100W in AC to a PSU, your electric company actually uses 200W and this is often shown in your electric bill as savings (depends on your electric utility company and your account with them). 100W is lost or wasted. Active PF Correction (PFC) power supplies usually have a PF of >0.95. Passive PFC units usually run 0.6 - 0.8. Non-PFC units usually measure 0.5-0.7. PF is not significant in terms of noise, heat or performance for a PC, but it is relevant to electricity consumption and energy conservation.

The Heath / Zenith SM-2320 digital display multimeter, a fairly standard unit, is used to measure the fan voltages and the line voltages of the PSU output. The latter is done via the terminal pin on the front panel, above the connections for the DC outputs from the PSU.

The Test Lab is a spare kitchen measuring 12 by 10 feet, with an 8 foot ceiling and vinyl tile floors. The acoustics are very lively and allows even very soft noises to be heard easily. The PSU under test is placed on a piece of soft foam to prevent transfer of vibrations to the table top. Temperature in the lab was 24C. This is something of a problem as PSUs usually operate in environments that easily reach 45C. Sited next to or above the CPU, the PSU is always subject to external heat. This brings us to the next topic...

In-case Thermal Simulation

The solution is a AC bulb in an empty case with the PSU mounted normally. The distance between the bottom of the PSU and the top of the bulb is about 7 inches. A 60W bulb was used for all the load tests up to 150W, then swapped for a 100W bulb for the 300W and 400W load tests. The bottom front vent of the case and its bezel have been modified for unrestricted airflow; the approximate size of the intake hole is the equivalent area of a 92mm fan,

The PSU must cope with the heat generated by the light bulb plus whatever heat it generates within itself. In a real system, there would be other air exhausts paths and mostly likely at least one case fan. So a Panaflo 80mm L fan was mounted on the back panel of the test case and connected to a voltage controller. The PSU was run through its load range with the fan turned on to 7V, about the level at which most PC silencers would run their case fan.

Noise Measurements

A highly accurate calibrated B&K model 1613 sound level meter on temporary loan from the University of BC's acoustics lab was used for noise measurements.

This professional caliber SLM dates back to 1978, weighs over 10 pounds, and is completely analog in design. It has a dynamic range that spans over 140 dB. The microphone used has a 1" diaphragm that's very responsive to low sound levels and low frequencies. The unit's absolute sensitivity reaches below 0 dBA -- at one point in the midband (1kHz) it was reading -4 dBA for background noise in the UBC anechoic chamber.

TEST RESULTS

Measurements were made at 5 output power levels: 65W, 90W, 150W, 300W and 400W. The PSU was allowed to run for ~10 minutes at each power level before measurements were recorded. The room temperature was 24C.

Table A. Load on the PSU*

+12V
24
36
60
144
168
+5V
20
20
45
80
145
+3.3V
16.5
26.4
39
69
81
-12V
2.4
3.6
3.6
3.6
3.6
+5VSR
2
4
2
2
2
TOTAL
65W
90W
150W
300W
400W

*The absence of the -5V line is not an error; the ATX12V v1.3 PSU Design Guide eliminates the need for this line. The load on each line was carefully readjusted to ensure the correct total power delivered.

Table B. On test bench, 24C ambient temperature

DC Power
65W
90W
150W
300W
400W
AC Power
89W
120W
195W
385W
527W
Internal Heat*
24W
30W
45W
85W
127W
Efficiency
73%
75%
77%
78%
76%
Power Factor
0.98
0.98
0.99
0.99
0.99
Fan Voltage
4.17
4.17V
4.2V
7.25V
11.5V
dBA @ 1 m
22
22
23
34
44
Exhaust Temp
27C
28C
29C
31C
33C

*The difference between AC input and DC output is lost as internal heat in the PSU.

Table C. In-case thermal simulation , over light bulb, with case fan turned off

DC Power
65W
90W
150W
300W
400W
Light bulb
60W
60W
100W
100W
100W
Case Temp
30C
30C
32C
34C
35C
Exhaust Temp
31C
33C
38C
41C
43C
Fan Voltage
4.17
4.17V
4.29V
7.8V
11.5V
dBA @ 1 m
22
22
23
35
44

ANALYSIS

1. EFFICIENCY was the very best ever encountered. Even at the low 65W load level where most PSUs fail to reach 65%, the Super Silencer started off smartly at an amazing 73%, climbing to 75% at 90W and 77% at 150W. The claimed 78% was reached at 300W output. Even at full output, it was still a high 76%. The efficiency of the Super Silencer 400 betters every other PSU tested at SPCR by a big margin.

These efficiency calculations are not errors, inadvertent or otherwise. All the load tests were repeated 3 times on two sample units. With the AC line voltage at 119V~120V, the results on all the tests fell in a range of less than 1% variance. The reported data is from a single set of tests on one of the samples.

The most practical result of this high efficiency is that the PSU runs cooler at every output power level compared to other models. The tables below illustrate it plainly. (The data on "other" models was taken from published SPCR reviews of real PSUs. These other PSUs were not named because there is no need to single them out for criticism; against the Super Silencer, all other PSUs' efficiency performance suffers.) The last column titled "% heat / waste" shows the percentage of increase in heat or energy wasted compared to Seasonic Super Silencer 400.

400W DC Output
AC Power
efficiency
heat
% heat / waste*
Super Silencer 400
520W
76%
127W
-
other 400
560W
71%
160W
26%
other 400
569W
70%
169W
33%
*
300W DC Output
AC Power
efficiency
heat
% heat / waste*
Super Silencer 400
385W
78%
85W
-
other 400W
410W
73%
110W
29%
other 400W
416W
72%
116W
36%
other 300W
420W
71%
120W
41%
*
65W DC Output
AC Power
efficiency
heat
% heat / waste*
Super Silencer 400
90W
72%
25W
-
other 400W
104W
62.5%
39W
56%
other 400W
98W
66%
33W
32%
other 300W
97W
67%
32W
28%

OK, enough about efficiency already...

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

  • +12V: 12.02 to 12.26
  • +5V: 4.9 to 5.09
  • +3.3V: 3.33 to 3.4

It should be noted that I have no way of testing line regulation, so AC conditions are steady-state, not dynamic as it would be (potentially) in a real PC; I have no way to vary input AC voltage at this time. The AC line voltage in the lab as measured by the Kill-a-Watt power meter is usually within a couple of volts of 120V.

3. POWER FACTOR was 0.98~0.99 at all power levels. Just about as good as can be. This may help you save money on your electric bill. In combination with the knowledge about the Super Silencer's high efficiency, ownership could evoke in you a heady sense of environmental righteousness.

4. NOISE was very low on startup. The sonic quality of the SuperRed fan has a a touch of bearing buzz. It is a fairly quiet fan, but not a Panaflo 80L (our reference quiet fan). At the 4.17V start and low load / temp fan voltage it is very quiet. No electronic noises such as coil whine or buzzing was heard at any time during the testing.

Noise measurements were made in the live test room in the evening. With all equipment turned off in the 23C temp room, the ambient noise was measured at ~17 dBA. The 22 dBA @ 1 meter measured on startup remained steady till the 150W load was reached, at which point the fan speed seemed to turn a corner and start to rise. The fan controller seems to have a clear "step" at 7~7.25V. That is, beyond a certain temp / load, the fan sped up from the low

The 22 dBA measured at low-med load is 3-4 dBA quieter than the Seasonic SS-300FS-APFC tested last year, which used an Adda fan*; it measured ~26 dBA in a quick check under the same conditions above. A similar quick check showed the Nexus NX3000 low-load noise to be about 20 dBA @ 1 meter.

*Seasonic Electronics USA informed us that the SuperRed fan has now replaced the Adda in the SS-xxxFS-APFC series, so its noise level should be similar to the Super series (except for the added turbulence of the earlier series' stamped-metal grill at higher fan speeds ).

5. COOLING: The high efficiency of the Super Silencer 400 allowed it to remain cool even in the tough in-case thermal simulation with a 100W bulb. Table B details the results, which are self-explanatory: It is the coolest running PSU yet encountered, and in a real system, running a system without any case fan could be a very viable option with the Super Silencer.

Usually, using the thermal speed controlled fan in the PSU as the only heat exhaust causes the fan to speed up as the PSU heats up, thereby adding back the noise removed with the case fans. The in-case thermal simulation results suggests this is not likely to happen with the Super Silencer, at least not with loads up to ~150W or more. Even at the 300W power level there was only a marginal increase in fan voltage and noise with the in-case thermal simulation.

A final comment on load testing:

Full power testing of PSUs for any length of time is a very demanding test, generally tougher than what real use conditions can demand. SPCR's bench testing is steady-state and can be extended indefinitely until the PSU burns; in real world applications, PSUs in PCs don't get this kind of abuse except maybe in a server room, which is a different application altogether, and the power demand on them varies up and down in a much more dynamic way, with average power loads rarely exceeding 150W for desktop PCs.

CONCLUSION

The Seasonic Super Silencer 400 represents a couple of major firsts for an ATX12V power supply.

1. It is the first to be compliant with the ATX12V v1.3 PSU Design Guide - as far as we know.

2. It is the first to reach an efficiency performance of 78%. That it achieves such high efficiency at a price no higher than many run-of-the-mill PSUs is a testament to Seasonic's intelligent engineering.

The noise level of this new model should be substantially lower in normal operation than previous Seasonic models. The Super Silencer also runs cool enough that in many systems, it is probably quite feasible to dispense with a case fan, thus eliminating another noise source.

It's clear that in real applications, inside a case powering a real system, the Seasonic Super Silencer 400 will probably run quieter than any other high power PSU we've examined or reviewed at SPCR.

Combine low noise with high performance, high efficiency, high current capability, handy "Doctor Cable" kit, 3-year warranty and a modest $99 price, and this new Seasonic looks like a real winner. The US$59 300W model is an even better deal for those with more modest power needs.

For diehard silencers and molders, the Super Silencer 400 is a perfect platform for fan swapping with the quietest fans available. Because of its super high efficiency and modest heat dissipation, the risk of overheating with low airflow fans is low. The end result with such modding would be loss of the generous 3-year warranty... and gain of the coolest quiet 400W PSU in the world.


Low Noise by Definition?

Regular visitors to SPCR may be aware that

Intel's ATX12V v1.3 PSU Design Guide has guidelines for low noise PSUs

. Section 5.7 on page 54 of the Guide calls for a maximum sound power level in a PSU designated as low noise to emit no greater than 4.0 Bels sound power at 50% load and ambient intake air temperature of 43C.

While 4.0 Bels is not exactly super quiet, the conditions of 50% power load and 43C air temp makes this a very tough standard to meet, especially for high power PSUs. Few PSUs even on our Recommended quiet PSU list would pass this test. Most quiet PSUs are quiet at power loads under 150W. But the high efficiency of the Super Silencer 400 made us wonder if it would pass.

It is very difficult to make a precise conversion of Bels (sound power) to decibels (sound pressure level), but 4.0 Bels would usually fall somewhere between 30-34 dBA @ 1 meter in most environmental conditions. In order to achieve the required 43C intake temperature, the 100W light bulb in the case was raised and brought closer to the intake vents while the PSU was running at 200W load.

This was an awkward process as the cover to the PC case had to be replaced, and a few minutes allowed to pass for internal temperature to stabilize. It was made even more difficult because of the thermal fan speed controller: It would adjust the fan speed up at first, causing temps to drop temporarily, then it would slow the fan down, causing the temp to go back up and so on... In the closest match to specified conditions, at an intake temperature of 41-45C, the noise level measured was 35~36 dBA @ 1 meter. The fan voltage was ~8V.

Given this SPL, the Super Silencer 400 probably would be borderline to pass the section 5.7 low noise guideline in Intel's ATX12V v1.3 PSU Design Guide. But it's likely to pass at 150W. The Super Silencer 300 at 50% load would be producing 150W. If its efficiency is anything like the 400, the Super Silencer 300 is a very good candidate to pass (with a better testing setup!) this demanding low noise guideline.


Our thanks to Seasonic and Seasonic USA for the review samples and for their kind support. They say Seasonic's new "Super" line of PSUs will be available any day now at 24 Fry's Electronics store locations around the US. They are also available online at quiet PC specialist

Silicon Acoustics.

* * * * *

Discuss this article in our Forums.


POSTSCRIPT July 20, 2003: ERRATA!

Despite all efforts to avoid testing errors, a Seasonic engineer did find a factual error (regarding the rating of the 12V line, already noted in the text of the review) and a procedural error:

"On page 4, the loading combination of 400W was over our specification of 3.3V & 5V combined load (not exceed 180W):

  • +5V~145W (29A) and +3.3V~81W (24.54A): The total power load of 226W exceeded the combined power limit of 180W
  • We suggest this load combination for 400W: +5V/110W (22A), +3.3V/69W (21A), +12V/216W (18A)
  • High combined load might cause shortened life, voltage out of regulation, high ripple noise...."

The most likely change in the result, according to Seasonic, is that the efficiency at full power may be improved somewhat. So the full power test was run again as per their suggested line loads:

+12V
+5V
+3.3V
-12V
+5VSR
TOTAL
216
110
70
2.4
2
400W

The end result did not change much. Instead of the 527W AC power consumption measured and reported with the overload on the +5V and +3.3V lines, AC consumption measured on 6 tries with both 400W samples was 523W to 526W. This was with the AC at 118~119V.

Although 523W is lower than any AC power consumption figure measured in previous tests, because the maximum was only 1W lower than before, it's hard to consider statistically significant. Even if the 523W figure is used for the efficiency calculation, the final result improves only from 75.9% to 76.5%. Thus, our original assessment of 76% efficiency at 400W remains unchanged.


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