Thanks much!  What I have now is one large 4TB drive (two separate 2TB drives RAIDed).  These are the following partitions: 200 MB EFI System Partition (1) 3799.52 GB NTFS Boot, Page File, Crash Dump, Basic Data Partition (OS C:/) 990 MB Recovery Partition (4) 13.27 GB Recovery Partition (5) 1.37 GB Recovery Partition (6) I have a few Dell Precisions (7740, 7750, and 7760) which I believe came in RAID mode.  Changing to AHCI was simple, just do the “advanced boot” or whatever it was to have the computer come up in Safe Mode, then reboot, F2, change to AHCI, save and reboot into Safe Mode, then reboot into normal mode and you’re done.  That procedure won’t work for this machine, apparently because there are two drives and the RAID is striped across them.  Bitlocker (enabled) complicated the issue but I was able to turn that off.  I am going to take some time to contemplate my options and figure out where I want to go with this.  I really don’t like the RAID configuration but I guess I could live with it.  What I really don’t like is Windows 11.  Another option I’m considering is downgrading to Windows 10 Home (although if I’m going to reinstall the OS, why not change to AHCI mode while I’m at it…).  Then, presumably, I could upgrade to Windows 10 Pro (already have the license key).  I appreciate the heads up about the potential warranty issues.  With the Precisions, Dell is typically very cool as far as modifications.  However, I understand that’s the Business side and not the Home side.  Another option that I am considering is purchasing or using a 1TB drive for the OS and a 2TB drive for storage and simply swap out the drives and then do a fresh install of Windows 10 Pro.  This would allow me to keep the existing drives for warranty purpose if a problem ever arose.  All I’d have to do is change the BIOS settings back to RAID. 
Hello, I just purchased an Alienware x17 R1 via Dell Outlet. It came with two 2 TB SSDs installed in a RAID configuration, and loaded with Windows 11 Home.  What I want to do is change from RAID to AHCI (I would prefer the SSDs be separate and not combined as a RAID, I’d rather have the OS on one of the drives, not striped onto both) and load Windows 10 Pro. I have a DVD with Windows 10 Pro to install. I entered the BIOS and changed to AHCI and disabled Secure Boot. That allowed the computer to boot from the DVD drive, but when I tried to install Windows 10 it wouldn’t allow it? There are a number of partitions on the drive and although the partitions can be removed, there doesn’t seem to be an option on the Windows 10 Pro install to reformat the drives prior to install, which is what I really want.  When I tried to install Windows 10 Pro from the disk onto the largest partition, it wouldn’t allow it.  I believe I could simply boot into Windows 11 Home and then run the install program on the DVD, but the problem there is that if I do so, I believe I would still be in RAID mode, which I don’t want. Any assistance in helping me get to “where I want to be” (AHCI with Windows 10 Pro) would be greatly appreciated!  I want Windows 10 Pro because =a) I want the Pro featuresb) I want to install the OS with a local account (not have to log into Microsoft).  Thanks!
x17 R1, switch to AHCI and load Windows 10, how to do it?