Thanks for your replys, it was to do with the ram, the cause of problem was the ram was getting too much volts. The Motherboard is on auto 1.6v and my dims are 1.5v so was an easy fix, just turned volts down in bios.
So by default the motherboard over-volted the RAM? This is unusual and usually a smaller level of extra voltage to the RAM won't cause a freeze up.
I really hope this fixes the issue permanently for you. I would continue to monitor the situation.