Thanks for the reply.
I'll have to have a look in my CMOS settings to see if I can edit the shutdown temperature.
Yes my CPU temp barely hits about 60 under an extremely heavy load. its around 20-30 at idle.
The power loss only happens during demanding games, which leads me to believe it could be almost anything. Graphics card, PSU requiring more power, faulty RAM, CPU overheating etc...
Will let you know how I get on

thanks again.