I am considering purchase of a silent PSU and the Seasonic SS-400FL is at the top of the list. I have a Fractal Define R2 case that has a bottom mounted PSU. I have heard that the Seasonic Fanless need to be mounted in a particular orientation. Would the SS-400FL be a good choice for that case?
The outside air would most likely be sucked in through the PSU. It's like this in my P183. This is good for cooling, but might be a problem for dust. I don't have much dust in the room, but I still mounted a filter on the PSUs outer side.
In the worst case you just clean the thing every once in a while.
As far as mounting at the top or bottom of the case, I'd say temperatures wise bottom is better, dust wise top is better. The orientation of the PSU itself should be as it says it should be, I wouldn't recommend turning it upside down.
Are the Seasonics still inflicted by coil whine issues?
Mine is, for example. I don't know if it depends on the electricity/wiring of the house or if Seasonic can do something about it. In any event, for me it's not audible unless I listen from up close, so it's not really bothering me that much.