My recommendation would be to buy the Corsair RMx/i series and advanced because oh my gosh it was at least less variable in noise production compared to Seasonic. To add icing on the cake, my brother bought Seasonic's Flagship Prime 650W PSU and it had the same loud coil whine as my Seasonic 460FL...
Mini ITX case is the Thermaltake F1 Suppressor; and it's sitting on the table in my silent room so I can easily pick up noise I7 6700 ASUS Dual GTX 1070 (do NOT get this) -gamed at 1080p in Overwatch and WoW maxed settings Corsair is much less heavy in weight and noise.
In order of purchase date: -460 FL: The loudest electronic noise out I heard of the bunch and that I've ever heard of; It's a mix of buzzes and clicks like a quiet but cheap hard drive; Was not tolerable to the slightest.