I have a Gigabye 7PESH2 motherboard that I want to put in the smallest case possible. I live in an apartment so I need to keep heavy mods to a minimum. Looking at the NZXT S340 and the Corsair Carbide R330 right now.
The Corsair Obsidian 750d fits motherboards of that size, but some stand-offs would not align because its not fully compatible. Its said to be the smallest case that can fit this kind of motherboard. Another PC case you can consider is the Silverstone FT04 case. It has full compatibility when the central Hard Disk bay is removed.
a video showing a SSI-EEB motherboard in the Corsair Obsidian 750D