hi gregrocker, to put is simply - you were right :-)
the problems with the booting were:
a) active partition on the raid field (fixed)
b) the F8 Advanced recovery options are not working (to be fixed)
The system is now entirely booting from the SSD, however, the recovery option is not working. I tried to rebuild it, but it did not fix the problem. Any ideas for a simple solution?
Performance - after the switch to AHCI, the booting time decrease by 20s (!). It changed from 60s to 40s (according to event viewer) - the HDD light was flashing nearly all the time (unlike in the RAID mode, where it stops frequently to take a breath). (I personally would blame the AMD driver implementation...and I get the feeling that AMD are getting worse and worse with driver support ( the graphic cards, mainboard, controllers), but this is a different story)
However, it was not possible to import the raid field into the system, therefore, I am stuck with the raid mode until I get more space to migrate the disks. Windows can strip data between multiple disks (raid 0). I have still to find out whether such a raid field can be accessed from other OS (eg. linux)
A strange thing was that when I removed the raid field and booted into Windows (nothing changed in bios, still in raid mode), Windows loaded a new driver for the SSD and required a reboot. This is strange as I have rebooted the PC 100 times since the SSD install and the RAID field is said to have no influence on a single SSD disk. Obviously it has!
many thanks for your time and input