Seasonic S12II: 330W to 500W of Silence

The Inside



Once the power supplies are open we are greeted by this very simple looking PCB. The first impression isn't all that great as the heatsinks look small, the component arrangement seems a bit haphazard, and the coloring almost makes things look dirty. However, looks can be deceiving. The first visible difference between the two power supply models can be seen in the different coils, main capacitors, and transformer. Since the design is the same and the components are from the same manufacturer, we will continue our discussion focusing on just one of these power supplies.



The filtering stage seems to be well arranged by Seasonic; it's starts on the small PCB at the AC inlet and extends to the upper side of the main PCB directly in front of the exhaust area. Seasonic has always taken a different approach with their heatsinks, which is very simple and almost seems cheap. Instead of using more expensive extruded aluminum, they just use metal plates where the fins are punched out and bent to the side. This way is by far the cheapest way to make a heatsink, and while it might not be as efficient as an aluminum design, with the high efficiency components Seasonic uses they should not have any problems with overheating.


There's also something to be said for their smaller heatsinks: large heatsinks tend to block airflow, and while the heatsinks might stay cooler surrounding components could actually end up being hotter. With plenty of open space, Seasonic's somewhat unique approach to power supply internals may be part of their reason for their excellent reputation of silence. Of course, having the power supply that isn't rated to provide 750W or more also helps with managing heat.