I think I have found the solution for blackout issue during gaming , my armoury crate was setup for temperature limit at middle , so it was becomes automatically blackout , when temperatures graduately increased & triggered at blackout , I have tried to set temperature limit at maximum , then everything was going normally. But still don't know why and don't have any solution when the phone becomes blackout or shutdown or restart when it's during charging.
There's only one solution left for this issue .. turn ur xmode off. I was facing the same issue with mobile data but with wifi it occurs less. So I tried all way at last I found phone gets heat up in gaming mode and screen gore's black out and I turned off xmode now I can play games while charging. Less cpu uses can heal this but if u want to play in hardcore xmode setting phone will heat up and black out.. play games without xmode is the only solution