It's pretty straight forward - just go into the BIOS and enable RAID under the SATA settings. Now, this won't necessarily put all your drives in RAID so it won't impact data on your current drives. Save the changes in the BIOS and restart.
With RAID enabled, you'll now have a new screen when your PC posts (Intel RAID option ROM or something similar to that). When you see this screen, you'll have to spam "Ctrl+i" to get into the RAID setup. You'll then see under the Main Menu, "1. Create RAID Volume". Select that, from there you'll have to enter the following:
- Name (just give the RAID array a name)
- RAID Level (pick RAID 0/Stripe)
- Disks (Select the disks you want to included in this RAID array. Any disks not included, such as your storage drive, will be listed as a "Non-RAID disk" and will be untouched. That said, if your data is very important, it's always a good idea to back it up just to be safe).
- Strip Size (128 kB is typically used. The way I understand it, this is basically how small the chunks of data will be broken down to when written to the disks).
When you have all this entered, just select Create Volume. From there you'll be prompted if you want it to be bootable, be sure to pick yes since it will be your boot drive. Once you're done, exit the RAID setup menu and reboot. You might have to go back into the BIOS to adjust your boot order again. You won't see your individual SSDs listed anymore in the boot order. The BIOS will recognize that they are in the RAID array and it will show the name of the array you chose above instead.
From there, just treat the array as any normal disk. If you're running Windows, it normally has no problem picking up the RAID array when you go to install since the Intel RAID drivers are on the disk already. Hope this helps!
Edit: cgipson1 beat me to it!