Thank you again for taking the time to help me.You can also do it without reinstall. But this requires creating bootloader on 500GB drive manually.
To create bootloader on 500GB drive, execute from elevated command prompt. Regular command prompt will give error on last step.
(if you get any errors, then stop immediately)
diskpartlist diskselect disk 1list partitionselect partition 2(select 505MB partition)delete partition overridecreate partition primary size=500format fs=ntfs quickassign letter=Hexitbcdboot c:\windows /s H:
After that shutdown and try to boot with only 500GB drive connected.
If all goes well, then reconnect 8TB drive, clean it, convert to GPT, partition and format it.
My 500 Gb drive is a M2 drive, so I cannot connect a SATA cable. I tried disconnecting the 8 Tb drive with the 500 Gb selected as the first device selected to boot from and it did not boot.
I also tried setting the DVD as the primary boot device with the 8 Tb disconnected and the machine did not boot.
It will boot to Windows 10 if the 8 Tb is connected, even when the DVD is selected as the primary boot device (BTW, I have 2 DVDs connected).
So, do I connect the 8 Tb and follow the directions above?