So here is the issue I am having. My BIOS boot mode is set to Legacy+UEFI and my Windows 8.1 installed as Legacy, however, when I try to install Ubuntu, it attempts to install as UEFI and doesn't detect windows and can't install GRUB properly. So I was wondering if there was a way to force Ubuntu to install as Legacy or if I need to completely reinstall everything.
Also, this is a custom built computer. The motherboard is an MSI Z87-GD65 Gaming motherboard.
First, verify that Windows is booting in BIOS/CSM/legacy mode. Windows 8.1 booting in that mode is certainly plausible on a self-built computer, but you should be 100% certain of what you're dealing with.
Second, the simplest way to get Ubuntu to boot in BIOS/CSM/legacy mode is to remove the EFI boot loaders from the Ubuntu boot medium. If you're booting from a USB flash drive, deleting the EFI directory tree on the flash drive should do the trick. There's also a Mac-specific version which, ironically, is BIOS-only, so you could download and use that.
