Non Boot Camp Supported Mac

I am wondering before I buy this product, if I have a copy of Windows 10 installed on a separate drive and booting between Mac OS X and Windows 10 requires me to have my old graphics card with EFI installed. I am looking for a more elegant solution. I have a third party non-efi Radeon Vega 64 Graphics card which I want to use only and not have the old graphics card taking up space on my Mac Pro 5, 1 and I want to be able to set the boot loader easily. Can this be done without using boot camp?

Others have done so and I wrote up this kbase: