Issues trying to set up Dual boot with Win 7 Pro

Using the tutorial you have provided, I attempted to set up a dual boot configuration using my existing Win 7 Pro on a Samsung SSD drive, and a clean install of Win 10 Pro on a fresh Kingston SSD drive. I created bootable Windows 10 installation USB, reset the UEFI Bios boot order and proceeded with the install. Win 10 installed, however it would not recognize the Win 7 Pro drive. I checked the UEFI Bios again, and the Samsung SSD was no longer shown in the "Fixed Boot Order Priorities". However, it was listed under "Hard Drive BBS Priorities", and under "Boot Override". It also shows up in Win 7 in the drives listings.

My motherboard is a MSI Z97 Gaming 5, with Click Bios 4 v1.9.

I must also mention, my Samsung SSD with Win 7 Pro was set up not with UEFI but Legacy boot. This was my first mobo with UEFI, so I made that mistake due to my ignorance.

I reformatted the Kingston Win 10 drive. Rebooted, but got error message that boot device not found. I rebooted and hit F11 to get back into Bios. A popup box gave me a listing of bootable devices and the Samsung SSD appeared. Selected it and it booted into Win 7 no problem. I went back into the Bios, but the Samsung SSD still not listed. I shut down the system, unplugged the Kingston SSD, rebooted, went back into Bios, and the Samsung returned.

I then shut down the system, connected the Kingston into a different SATA port, rebooted the system, went back to Bios, and the Kingston remains unlisted in the "Fixed Boot Order Priorities" as before, but shows up in "Hard Drive BBS Priorities", and under "Boot Override". It also shows up in Win 7 in the drives listings. Remember that the Kingston is just formatted, no op system installed on it.

This has me perplexed to say the least.

Oh and FYI, I set up the Win 10 install on the Kingston SSD as a legacy drive too.

Another question I will ask is can you have one operating system on a legacy drive and one on a UEFI drive in the same PC?

Thanks in advance for your help!

The best way to create a bootable Windows 10 USB flash drive.
USB Flash Drive - Create to Install Windows 10 - Windows 10 Forums
OPTION ONE: Use Media Creation Tool to create Bootable Windows 10 USB for Legacy BIOS and UEFI.

Do you know how to choose the Legacy BIOS or UEFI boot mode?
Depending how the Windows install media is booted (Legacy BIOS or UEFI) Windows creates either MBR or GPT partition table on the SSD/HDD.
- The non-UEFI option will boot the Windows install media in the Legacy BIOS mode and Windows Setup will create the MBR partition table automatically.
- The UEFI option will boot the Windows install media in the UEFI mode and Windows Setup will create the GPT partition table automatically.

DasDonster said:

Another question I will ask is can you have one operating system on a legacy drive and one on a UEFI drive in the same PC?

No.