finally there is an end to this!!
Not so much a resolution but a solution.
I bought a new machine for the core - clean DVD install of 710.
Booted this MD and seems to have gone though generation of machine image.
All seems to have worked first go
Thanks Zaerc for your input trying to get to the end of this!! in the end this motherboard seems ok so far.
vga only at the moment, need to verify DVI/HDMI operation.
I've added it to the wiki and will update as I progress.
Before I nuke the old LMCE partition on my other dual boot machine is it worth looking at this old install with a view to check why this was failing?
p.s. UI2 overlay looks sweet and has a high WAF