A) Make sure to use at least 2 HDD for onboard raid controller
B) Enter BIOS setup with 'Del' button during POST and change SATA configuration from 'AHCI' to 'RAID' mode. Then choose Intel or Adaptec if available
C) Change BIOS boot order to use device with Windows files as first boot media, Save and Exit BIOS
D) Windows installation screens should start after reboot. When you get to screen asking which drive to install windows, load SATA drivers from a portable media such as USB flash drive or similiar and the RAID disk volume should appear
E) On reboot, change BIOS boot order to use RAID volume as first bootable device
F) After logging into Windows, install drivers such as Intel Rapid Storage Technology or Adaptec equivalent to manage RAID