Right after a full days worth of messing about I have found out what was causing the shutdowns it was the SB voltage.

I initially upped the NB & SB voltage almost together with the CPU drive set on strong as its the only way the board would boot. I have now found by switching the CPU drive to weak I can significantly reduce the SB voltage needed yet it will still allow me to up the NB voltage.

I have run 12 attempts at 462.5fsb x 8 = 3.7GHz today all ending between 20 minutes & an hour & a half with an Orthos fatal error rather than a shutdown.

From this I come to the conclusion that 3.7GHz isnt going to happen with this E6400 on air despite it being 5 hours+ Orthos stable on small fft's.

I reduced the fsb to 1825 456.25 x 8 = 3650MHz & it ran Orthos for 8 1/2 hours on blend until I stopped it.

Regards

Craig.