Hi All
I finally managed to upgrade to 8.1
As I said, I was suspecting the problem to be related to my MoBo, a Sabertooth x79. So I uninstalled everything related to Asus, such as AI Suite II and the various utilities that the ASUS updates had installed over time. The only thing that I left was Intel's Rapid Storage.
Not only did this really improve the performance, but the upgrade from the MS store (after having done a wsreset) went ok. Haven't checked everything yet, I'm now applying the windows updates.
Happy it finally worked, especially without having to re-install all my sw.
BTW, I saw somewhere people considering Logitech's devices as a possible culprit, I have both a Logitech kpd and a mouse over a unifying wireless receiver and they remained on the system during the upgrade. So (at least for me) Logitech's not guilty...
Good luck to all of you still trying!
cool, wondering do you have Intel Management Engine Components installed before hand?