Seasonic S12 Energy Plus: Efficient Power for Connoisseurs

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Each of these recording have 10 seconds of silence to let you hear the ambient sound of the room, followed by 10 seconds of the product's noise.

Sound Recordings of PSU Comparatives


These recordings were made with a high resolution, studio quality, digital recording system, then converted to LAME 128kbps encoded MP3s. We've listened long and hard to ensure there is no audible degradation from the original WAV files to these MP3s. They represent a quick snapshot of what we heard during the review. Two recordings of each noise level were made, one from a distance of one meter, and another from one foot away.

The one meter recording is intended to give you an idea of how the subject of this review sound in actual use — one meter is a reasonable typical distance between a computer or computer component and your ear. The recording contains stretches of ambient noise that you can use to judge the relative loudness of the subject. For best results, set your volume control so that the ambient noise is just barely audible. Be aware that very quiet subjects may not be audible — if we couldn't hear it from one meter, chances are we couldn't record it either!

The one foot recording is designed to bring out the fine details of the noise. Use this recording with caution! Although more detailed, it may not represent how the subject sounds in actual use. It is best to listen to this recording after you have listened to the one meter recording.

More details about how we make these recordings can be found in our short article: Audio Recording Methods Revised.


For a high end, blazing performance, dual-graphics, overclocked monster of a system, we know of no quieter power supply than the Energy Plus. Acoustically, the Energy Plus has surpassed our expectations of what is possible from a quiet power supply and set a new standard. With a fan that doesn't begin to increase in speed until 250W output, it will take a concerted effort to force the Energy Plus to become noisy — a nice change from the need to put effort into preventing added noise.

One question that we have is whether the quieter performance has come at the expense of cooling and reliability. That's not to say that the Energy Plus is undercooled, but it doesn't quite measure up to the excellent thermal performance that we saw in their original S12's. That said, the high 550W and 650W capacity points mean that they should operate well below 50% load most of the time. With that much headroom, it's hard to imagine the cooling system being inadequate.

As expected for an 80 Plus power supply, efficiency was top notch, and the 85% peak very close to the highest we've measured. That said, the high efficiency does need to be put into perspective. A little extra efficiency is nice to have in a powerful system, but an extra two or three percentage points doesn't work out to much of an energy saving unless the load is ridiculously high — which kind of defeats the purpose. In the range that most people will use it, the Energy Plus models are not any more efficient than Seasonic's existing models.

The biggest strike against the Energy Plus is its price. US$150 for a power supply is far from pocket change, and there are plenty of cheaper alternatives that are just as quiet at lower levels. To reiterate: The Energy Plus is a power supply for connoisseurs: It's engineered beyond what most people need, but if you're looking for a special power supply for that special system, the Energy Plus fits the bill perfectly.

Nice as it is, we can't help asking where are the lower capacity models that perform like the OEM models that we've already seen from Seasonic. We know they are capable of building a power supply that is 84% efficient at 65W. Where is the 330W Energy Plus that can match the SS-300SFD for low-load efficiency? Here's to hoping Seasonic brings one out for energy conscious silent PC enthusiasts.


SPCR Articles of Related Interest:
Power Supply Fundamentals & Recommended Units
Power Distribution within Six PCs
Seasonic S12-330 PSU, New Sleeved Version
Seasonic S12-430: Our current low-noise champ
Seasonic S12-500 & S12-600 Power Supplies
Seasonic SS-330SFD 80 Plus: Little Big PSU
Seasonic SS-400HT Power Supply, 80 Plus Version

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

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