Download a program like afterburner and check to make sure your CPU isn't going absurdly high (anything above 80c can cause fail safe restart), and your GPU isn't shutting down due to thermal throttling not being enough (your GPU temps are above 100c)
Else check for Nivida drivers and update them. Run a virus scan, run system file checker for corrupted windows files, or reset your windows via the windows 10 reset feature.
Another possibility is just that fortnight or whatever is designed by filthy plebs, therefor like PUBG it is crashing irregularly. In this case I suggest verifying game cache or reinstalling the game.