Seasonic X-Series SS-460FL: 460 Watts of Fanless Power

SS-460FL: Good and silent, but is that what you really want?

With a price of $160 online the Seasonic X-Series SS-460FL is as expensive as some previously tested 1000W power supplies. However, it offers the best performance we've seen and a fully modular connector panel. We've never seen a PSU that has no real weaknesses in our testing, and the worst thing we can say about the SS-460FL performance is that it only posted 80% efficiency at 10% load (which is still good).

We even managed to draw 110% of the rated output with reliable results, although it is difficult to assess what the performance will be after a few months of operation at high loads and the higher temperatures of summertime. If you're planning on running close to a 100% load with an entirely fanless system, we suspect you'll have difficulties, but provided you isolate the PSU from other heat sources it should hold up. Then again, finding fanless GPUs that require PEG connectors for power is hard to do, and that would almost be required to hit the 460W mark—that or a heavily overclocked CPU, neither of which would make much sense if you're after silent operation. Exercise some care in speccing out your system and err on the side of reason and the SS-460FL should perform admirably.

While you can't plug in all peripheral cable harnesses, the SS-460FL has two PCIe connectors—not bad for a passively cooled PSU. (Note that the 400W model only comes with a single PEG connector.) All of the cables are longer than 60cm as well, so you can safely use this unit in some larger cases. All the chosen components are upscale and the design and topology is outstanding. There is a line filtering stage (Yunpen) behind the entrance and Nippon Chemi-Con capacitors are used throughout the PSU. The Infineon transistors are well dimensioned and the attachement of the PFC-choke is adequate. And just in case something goes awry, Seasonic offers all the expected safety functions.

The SS-460FL reached up to 91% efficiency, with no more than 12mV ripple and noise on all rails and good voltage regulation. There's no fan to make noise, and the electronics are also free of static or any other unwanted effects. The PSU is exactly what you'd expect: silent. Even so, there's some serious competition for the X-Series Fanless models from Seasonic's own product line.

The semi-passive X-Series models are able to deliver more power, thanks to the addition of active cooling that kicks in at around 20% load and only really becomes noticeable above 50%, and you get all that for the same (or a lower) price. This includes the SS-560KM, which bumps up the maximum output and can still run silently under light loads, or near-silent at moderate loads. Considering you can get that unit for $30 less than the SS-460SL, and the peace of mind the "backup" Sanyo Denki fan provides, for the vast majority of users we'd recommend that route over a fanless PSU.

If you want to have an absolutely silent PSU that can run at high loads and you don't care about cost, the SS-460FL delivers. What we can't readily quantify is the long-term stability and performance after months or years of use. The SS-460GL is a prestige object that most will find unnecessary, but it's still an awesome product. For all other customers the SS-560KM is nearly silent through ~50% load and passive at low loads, and it represents a more reasonable selection for midrange PCs. After all, why bother with a silent PSU if you're still running fans on the CPU and GPU?