No, I am not using a NAS server, I am putting the two raids in the same motherboard (asus z170a). This mobo gives support to RAID.
I have already done it. It is possible doing it manually in the bios setup (using the automatic ez... process I lost the boot for windows, but the data is still there and linux is working on my previous RAID 0), the automatic method doesn't allow to choose the desired drives for the RAID. But I configured manually a new RAID5 and linux is detecting it and everything else seems to be working well.
I hadn't found any answer to my question, so I copied my data and I tried it myself.
Thanks anyway