SPCR

I am building silent passive PC. Haswell, 530ssd, 2 dims, MB inter, video from haswell.

Seasonic fanless looks like good chose, which one will make less buzzle noise 400W 460W or 520W, which version is better for my needs?

For the pc you are building, you could even por it by pico psu.

Or if you want an atx psu, I would consider a seasonic g 360. But if you want fanless, iconsider kinwin striker 500 or rosewill silentnight 500, both have been reviewed by spcr and came as editor choice.

Total power draw might be around 100W in real use. For that kind of power consumption you'd be better off keeping the power supply size down and I'd definitely second the PicoPSU. What kind of case are you intending to use? If you can use a PicoPSU then you could also make use of a smaller form factor like MiniITX because you have no need for any expansion slots. Reducing the size of the motherboard will also reduce power consumption further.

I've been very happy with my Seasonic 400 fanless. Completely silent. Early on there were a few complaints about whine, but I haven't seen any more in years.

But as mentioned above, it's probably overkill for your build, and expensive to boot.

I can use both ATX or mATX, don't care much. Also don't care to may more for power supply. the only thing i car - is buzzle noise.

I usually keep my fanless cases open but if i can archive really low power consumption i can go for closed case.