Hi absic, thanks for the reply.
Yes, the internal SATA controller is set to RAID and I used for Windows install an optical drive running UEFI boot type, as suggested by Gigabyte support in another forum.
But I must confess that I don't understood the CSM setup found in the BIOS if using W8.
Just updated to F8b BIOS before another unsuccessful install, half hour ago.
Hardware added is very plain, the ADATA SSD and a LG blu-ray only for install plus the i5 CPU and the Corsair memory.
The mobo will be used for robotics management so I must to keep things simple and efficient using the M.2 device.
But with such ugly figures probably I will switch to 2.5" SSD if that M.2 can't do the job. Very sad, it was very expensive.