So I've gone through the ThermalTake PSU Calculator & added everything to the list.
Overclock,Vcore, SLI setup, SSD, HDD, ODD, Fans, USB Devices & Cap aging. Aparently the recommended wattage is 620. I've contacted the seller as it's still covered under warrenty to see if I can get a replacement. It doesn't crash just playing BF3, only when benching, so I've stopped benching.
Should I really have this issue 12-13 months into using it?