Game keeps crashing

[MatchuEnsmith]

One of my friends computer keeps crashing, he is running a Fx-6300 with a Rx 480 4gb and 2x4 gb sticks of gigabyte ripjaw ddr3 1866 memory. He doesn't have any overclocking and his Cpu and Gpu temperatures are fine. It doesn't happen every time he plays but still quite often and it only happens when he is playing Overwatch.  All of the sudden his screen goes black and the application closes and says rendering device lost. If he closes Overwatch and Blizzard, he cannot open them again until he restarts his computer.  Also he has the Roccat  Sova keyboard and whenever he boots his pc , it refuses to turn on until the keyboard is unplugged. Any ideas on how to fix these problems? He already updated his bios and installed the latest drivers.