Edwin said: View Post
Make sure you have your backups in order! :)
So there was one wrinkle. Only one drive can be marked as "System" and that's where boot is handled regardless. In my case it was the Windows 7 drive. I tried disabling the SATA controller for that drive and sure enough it would not boot the Windows 10 drive. What I had to do was run the REPAIR option off my install disk and choose "ADVANCED" then "AUTOMATIC REPAIR - Fix problems that keep Windows from loading" and viola! It marked the Windows 10 partition as SYSTEM and after reboot it loaded normally.

Then I re-enabled SATA 0 and only then did I delete the old Windows 7 partitions off the old drive and re-partition it with a clean NTFS for data

Now I have a 100% Windows 10 machine Thanks for the help guys!