@cvectra BIOS upgrade/downgrade doesn't affect SLIC on Intel boards. Make sure there's no loader installed (check from Windows PE or live Linux media). As @LatinMcG mentioned, use v7 of the OA2Intel tool.
Thanks, BUT @LatinMcG + @Tito I did use Version 7 and I ran it (oa2intel v7) from plain DOS several times without success Any other proposals or tools?
Solved I booted from USB Stick into Windows , ran Oa2intelwin, rebooted again from USB into Windows and surprise, surprise SLIC Toolkit shows the new marker Booted into Windows from hdd and SLIC Toolkit again shows the old marker: _ASUS-Notebook, SO it was clear that their has to be a loader installed or something else... Now I will try to remove this loader. I googled and found some info: Boot in safe mode -> command prompt: bootsect /nt60 all bootrec /fix mbr bootrec /fix boot bootrec /rebuild bcd I hope this will remove the loader ....