If there are no data on the drives then there is not trick, just go into the RAID bios during post and configure a RAID 1 array with the 2 drives. Just make sure you isolate the other drive and dont use it by mistake.
Thanks a lot, for your help!
in fact there is, in one of the data disks. I assume, by your answer that I have to backup it. I had the hope that this data could stay on the disk and that after configuring it would be copied to the other disk....
but that's only a small inconvenience, thanks again!
Intel's raid stack does support preserving data. In the Matrix Storage Console, select "Create From Existing" (or something like that). You will first select the source disk (the one with data on it) and then you can select your other disk(s) for the volume.