it will be very useful to understand what are you booting with the USB key?
How is the usb key formatted, fat32, ntfs?
Do the USB ports work fine with the OS that came with each system?
Did these systems come with Windows 10 or Windows 7 downgrade? this will determine the BIOS settings, like SecureBook, and UEFI native (for example) that could affct what you are trying to boot
Again, details are important