well for a start your gonna have a slight bottleneck if you havent oc'd the cpu.
if you already have oc'd it then maybe its a little unstable... try turning it down a little to see if it becomes stable. if it does then turn it back up and apply a little more voltage to the cpu and or North Bridge.
also check the event logs. crtlpanel/admintools/eventviewer. applications...
chances are its a driver quitting and failing to restart for some reason .