Dual Boot No Boot Menu

Ladies and Gentlemen
I am in a new arena and need some help. I have been in the INI and BCD Arena but not the EFI MBR.
I decided to go with a new motherboard and AMD RYZEN CPU. I set up the new system and moved my hard drives with Windows 10 Pro 64 bit and Windows 8.1 Pro 64 bit. The system booted up and the courser jumped several places on the monitor as it booted. No boot menu appeared but the system booted up to Windows 10 (default Boot) no problems. After the system was stable new drivers etc. I began to search for a way to get the boot menu to work. Since the boot menu was not appearing, I decided to let the Windows 8 disk repair the boot setup. No luck with start up repair. I then decided to refresh the drive, no luck (Drive Locked). Next I decided to install Windows 8 on the same partition.
When I started the install for 8, I got the message Windows cannot be installed to this Disc. The selected disk has an MBR partition table on EFI system, Windows can only be installed to GPT Disk.
Not knowing what to look for, I decided to post this on web.
Any Help, Suggestion we be appreciated.

Closely related to topgundcp's answer on:

How to move the boot status from a partition to another ?

I don't know what is going on with the MBR's. I know that Windows 8 will not install on the partition that it was on with the old MoBo. I now have moved Windows 8 to a second hard drive and with the partition blank, cannot create a partition with Win 8. I still get the message that Windows 8 cannot install on a EFI only will install on a GPT MBR.

because

Cannot clean install windows onto MBR partition with the
installation that has booted out of UEFI / GPT partition

Cannot clean install windows onto GPT partition with the
installation that has booted out of MBR partition

Get RUFUS, make bootable Windows installer with GPT partition (3rd selection), need product key prepared windows installation ISO.

Check your computer BIOS, F2 or other F# varies slightly it depends.
Go to 'boot' tab
Inspect whether or not there's EFI boot option

start normally

if there's EFI and want to utilize it:

Need gdisk32 (or 64).exe or ,
for convenient usage use paid 3rd party software, such as EaseUs Partition master
in order to convert to GPT par.

back to bios pick the EFI boot and USB flash boot option enable
install windows to a just-converted-to-GPT partition

Hello, @ Clockman. Welcome to Windows TenForums.

Asus board here as well with a UEFI BIOS. What you’re attempting to do will not work, for your drive is formatted with an MBR scheme, which will only boot your 10, but demands a GPT scheme to run under UEFI properly. You’ll need to wipe the disk and start over. Here’s a few ways to achieve that:

DISKPART - How to Partition GPT disk Installation Upgrade Tutorials

Dual Boot Windows 10 with Windows 7 or Windows 8 Installation Upgrade Tutorials

CASE CLOSED
I tried to work with UEFI Using Dual-Boot Repair, because Windows 8 gave me the error that it could not install on a EFI Disc. After trying to find out the problem, I gave up and just decided to try something else. That something was EasyBCD. Using EasyBCD I erased all the Boot data in the BCD boot file and let it search for all Windows that I could boot from. EasyBCD found the following Windows 10 and Windows 8. I saved the boot configuration and restarted the computer and I had a boot menu with both 10 & 8 listed. I selected 8 and after installing what it needed to start up the desk top for Windows 8 appeared.
Then the unexpected happened. It smell worse than a rotten EGG in you computer room.

I hope you can read the above.