I am using a 16GB kingston USB3.0 stick with Hive OS on it and it works great.
The 3 molexes on the MB are not connected, I have powered risers (2 per cable coming from the PSU).
Risers are something fishy, sometimes have to switch either cables or power them from another PSU until everything runs fine.
If they have an issue with power the MB shows multiple slots in red, its just figuring out which one to change PSU then and everything is green again.