how get rid of RAID?

I have a Precision T3500 with v.A17 of the BIOS.  It has Win7 Pro on the HDD, and I have just added an unformatted SSD.  Now that there are 2 SATA drives seen by the BIOS, there is a splash screen during POST that reports: "RAID volumes: None defined".  I want to get rid of that splash screen and the overhead of RAID.  But if  I change the "SATA Operation" setting in the BIOS from "RAID On" to "RAID Autodetect/AHCI", there is no splash screen, but Windows freezes during boot-up.

I believe that if I clean-install Win10 Pro on the SSD with the "RAID Autodetect/AHCI" setting in the BIOS, I can get rid of RAID, but I want to keep the HDD with Win7 Pro on it for backup and to access the files on it.

1)  Would the clean-installed Win10 on the SSD be able to read the files on the HDD?

2)  Is there a way to boot the Win7 on the HDD without changing back to the "RAID On" setting in the BIOS?

TimDaniels