ARC / all
An update - and I know I am stupidly tempting fate.
Since my last BSOD (before which I physically removed Xonar card and main drivers and updated GPU drivers still but still got a BSOD) I have used Driver sweeper and found more Asus sound files which I also removed.
Probably unrelated (and maybe had no impact) but I have not yet removed Plantronic Headset drivers (C media) but did remove headset from USB.
Whether by pure chance or by Sim City continue issue of file updates, no more BSOD's since.
I will keep my eye on this and see what I can add back in terms of using the Xonar card.
Someone suggested these drivers:https://brainbit.wordpress.com/category/uni-xonar/
where much better - any feedback here ?.
I will I think stay where I am for now and hope for continued stability.
Again all - thanks for your help to ger to this point.
(I just know after this positive mail it will go tits up again tonight....)