Seasonic Super Silencer 400 - ATX12V 1.3

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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 <35 dBA (presumably at 1 meter).


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
Max Current
Max Output
Peak Output
Total Output

*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
Voltage Regulation
Peak Current*

*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:

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