Seasonic SS-300SFD 80 Plus: Little Big PSU

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MP3 Sound Recordings of Seasonic SS-300SFD 80 Plus

Seasonic SS-300SFD 80PLUS @ 90W (22 [email protected])

Seasonic SS-300SFD 80PLUS @ 150W (25 [email protected])

Seasonic SS-300SFD 80PLUS @ 200W (30 [email protected])

Seasonic SS-300SFD 80PLUS @ 250W (34 [email protected])

There was no need to make recordings at higher power levels; it's simply too loud.

Sound Recordings of PSU Comparatives

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

Antec Neo HE 430 @ 150W (21 [email protected])

Antec Neo HE 430 @ 200W (26 [email protected])

Nexus 92mm case fan @ 5V (17 dBA/1m) Reference


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.


It's easy to see a commercial system integrator using this PSU for a quiet custom media PC. The only real question for DIY builders who want to use this power supply is, "Which case?" A lot of microATX cases appear to be set up for ATX power supplies. Some do take SFX12V power supplies, although they usually come equipped with one. The very small ones tend to be barebones types with proprietary power supply types.

Finding a microATX case with the kind of free-flow characteristics ideal for silent computing may be a challenge. We have to admit we have not looked hard for one before.

This model would be a good quiet replacement for a case that already uses an SFX12V PSU; as mentioned, there have been lots of big-brand computers that have used this form factor. Another option is to seek out the metal adapter templates Seasonic used to include with their Super Versatile 200W SFX12V PSU; this allowed the microATX PSU to be used in any ATX case.


We don't really have any other SFX12V power supplies to compare directly with this model, but the few I've seen in the past have all been loud and much lower powered. The only exception has been another Seasonic, the SS-200SFD I used in my Breadbox PC a few years ago.

This latest iteration, despite its generic looks, is something of a find for custom quiet PC builders. It's small yet quite powerful, highly efficient in converting AC to DC, and pretty quiet all around. The maximum power output of 300W is plenty for something like an Athlon 64-based media center, or even a midrange single video card gaming rig; there is plenty of juice on the 12V line.

The power delivery was excellent throughout testing. Voltage rails were very tightly regulated, and it delivered the full rated power without complaint. Cooling was excellent even at high loads. Operating environments that are hotter than the 40°C seen by the PSU at full power in the test box might cause faster fan speed ramp-up, but most system builders will not subject this PSU to such high steady steady power load, anyway.

The stock fan is not bad, though it could definitely be improved. The ADDA fan used in the Antec Neo HE series would really make the SS-300SFD shine acoustically. Aside from the slightly mediocre fan, what's not to like in the Seasonic SS-300SFD 80 Plus?

Much thanks to Seasonic USA for the opportunity to examine this power supply.

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