i hope it is a good psu that you are using. that's a beefy graphics card you have there.
try running the system with just one ram stick and then see if it still reboots. check with both ram sticks.
Also there must be an instruction in your mobo manual which says something like " note, core series processors require ram in slot no 1 for the system to work properly"
For my system, it is necessary that for stable operation, i populate slot 1 with a ram stick.