Thanks but i pritty much ruled all that out as i have tried it on 3 different hard drives, the drive i use for maya, my games drive (which also has everything up to date) and also a spare old 20gb drive which had new clean installs of XP and then Vista, all had the same performance in Maya but only the viewpoints are slow, renders are fast.

On my single core now, everything is back to normal again.

I have ordered a bios chip for the other board, will hopefully get that going at the weekend and will let you know.

I even tried last night messing around with the affinity settings, even tried another app to alter the settings between the cores, e.g. only core 1, only core 2 or both cores, no difference.