Hi I have same problem with my Asus Formula 2.
When I play Silent Hunter 5 my PC just turns off and in BIOS I get error message.
NB temp hi.
I bought motherboard a year ago and I really don't know why it just of a sudden starts malfunctioning.
When it is under load it starts shutting down.
I had EVGA motherboard it was doing same thing when it's capacitor got fried.
So because of that I bought MAXIMUS.
I haven't clocked or done anything to config.
Maximus II Formula
Core2 Quad CPU q6600
NVIDIA GeForce GTS 250