@Entonite Well lets start with one problem at a time. First off, lets go with the issue of arma 3 locking up. Have you checked your gpu temps? Are you running the latest drivers? Does it lock up ONLY with that game, or any game you run? Are you overclocked or on completely stock settings? Have you checked your memory timings and voltages in the bios to make sure they are set accurately?
It can be a pain in the ass to jump onto a new platform and have issues, but rest assured we will get them figured out brother.