Well, I've made some progress since this initial post. I read a few more posts on other sites and increased CPU VTT to max out at 1.55 volts. System boots fine now. However, games crash now about 5 mins in, not sure what to change next. I'm using a 9x multiplier, 1333 fsb and 3:2 ratio.
ok, at stock, according to CPU-Z, Vcore = 1.28V. I increased this to 1.29, still crashing, then increased it to 1.3, still crashing. Should I be increasing the NB / SB voltage at the same time as doing this?