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?

Are the Seasonics still inflicted by coil whine issues?

The ss400fl should be mounted top up, so heat can rise and get out of the psu, i dont think you should have any issues with it mounted in the bottom.

Mine is perfect, dead silent, but there is a small amount of users that have reported a buzz sound, this is not particular to any model, im really happy with mine, but if you dont want to risk it, check also KINGWIN STR-500, in case you are interested,

SPCR Fanless PSUs: Kingwin Stryker STR-500
JonnyGuru Reviews - Kingwin Stryker Fanless 500W
HardOCP Kingwin Stryker STR500 Power Supply Review

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.


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.

Thanks for all your feedback.
I just finished the purchase today. There is a reasonable deal on at Newegg.
I am gambling that a positively pressurized case will be okay with the fanless PSU.

Here's my current setup:
2 Nexus silent case fan 120mm - Intakes (front)
1 Cooler Master Hyper 212+ 120mm CPUfan
1 Nexus silent case fan 120mm - Exhaust (rear)
1 Seasonic M12II Bronze PSU 120mm - Exhaust (rear)
1 Sapphire HD5770 VaporX video card 60?mm Noisy Fan

With the above setup the case has a small positive pressure so I am assuming with the removal of the PSU fan the pressure should rise slightly and the PSU should have airflow.

Next challenge will be the ATI video card. Sapphire 5770 VaporX is supposed to be relatively quiet but I'm thinking it is the noisiest component I own. Passive would be nice but might be a case of wishful thinking.

I have a problem with this Attention that PSU must be mounted with UP pcb direction in the case, which is reverse than major active PS units. Well that is HUGE problem to me because with that direction it can not fit in my CHIEFTEC HB-03 case, but in DOWN direction it can. That is really strange because this PS unit is made for low HTPC cases, and this CHIEFTEC is one of the most quality cases and not really cheap.

What should I do? Can I mounted with opposite DOWN direction (like majority of other PSU) because it CAN fit in that way? Is it dangerous that in that case PSU can be overheated or maybe make a fire in my case?

Other thing that I don`like is because the case is very low, classic size PSU (like this one) do not have a space to "breed", so the active one have very loud fans, and this one transfers heat to the rest of the case. In my case, CPU cooler is louder because the CPU is much warmer than with active PSU.