Seasonic X-400 Fanless PSU

With the evolution of some power supplies being able to be near silent, I figured we would not see any new completely fanless PSU’s coming out. I was wrong. Seasonic follows the likes of Antec and FSP which discontinued theirs and has released a completely fanless PSU for your system. As always, make sure your system has adequate cooling for these. (Btw, if you can find the Antec Phantom 500 used, it’s an awesome passive PSU)


The X-400 Fanless or SS-400FL is the first of two fanless models in the Seasonic X-series power supplies. A 460W model is scheduled to hit the market in September. The X-series is intended to span eight models, with the fanless units at the bottom and 1000W and 1200W models at the top. As SPCR regulars are well aware, a Seasonic X-650 reviewed in November 2009 garnered very high praise and earned our Editor’s Choice award. Aside from superb electrical performance, the X-650 featured a successful "hybrid" cooling system — hybrid meaning a cross between passive and active cooling. Its fan simply stopped spinning at loads below ~200W in our hot test box, putting the X-650 at the top of our quiet PSU roster. Interestingly, some of the newly announced 80 Plus Gold Corsair AX series power supplies appear to be direct family relations to the X-series.