I have a Precision M4600 that is running Windows 8.1. It is a bitlockered install and boots via the UEFI BIOS. I am trying to install Windows 10 on a new clean hard drive that I will use in place of the current Windows 8.1 drive. I need to be able to go back and forth between the 2 drives until I have everything running as expected on the Windows 10 drive. When I boot from Windows 10 media and run through the install onto the new hard drive...when the system reboots it says no system disk found. If I hit F12 during boot and then select the hard drive from the Legacy menu...it boots fine. How can I correct this with out losing the ability to go back to the Windows 8.1 drive?