Thank you for contacting the Intel community.
Would you please attach a picture of the Intel® Rapid Storage Technology where you are seeing this behavior? This is to have a better view of the issue.
Also, I will appreciate if you can attach a picture of the device manager as well.
Thanks for your reply.
When I re-entered the boot-up screen via Ctrl-I to get a photo of it, I noticed it thought there was a degraded RAID present, even though I had reset it via this screen previously.
From this I deduced my error:
After resetting the raid last time I had the following:
Intel Controller connected to Disk 0 (SSD Drive) and Disk 1 (WDC HDD)
On-board controller connected to Disk 2 (SSD Drive) and Disk 3 (WDC HDD)
I then combined the two WDC HDD's into a striped volume via the Windows Disk Management Console.
This confused the Intel software which saw that one of the drives on the Intel Controller was in a RAID, but it could not see the other drive (because it was attached to the on-board controller).
I think the solution to the problem (which worked for me) was to not make a RAID array using Windows to combine one drive on the Intel Controller and the other drive on the on-board controller. This will confuse the RST software.
Problem solved, thanks Ivan.