Suprisingly OS X actually has decent support for a wide array of video cards out of the box, all of the AMD GCN 1.0 (7000 series and the R7/R9 2XXX rebrands of them) work out of the box as does the R9 290X/390X, along with a bunch of the older HD4000-HD6000 cards. NVidia provides native drivers for all their cards online, and if you're using an Intel GPU that was ever in a Mac it has support as well.
Of course, it's in violation of the macOS EULA to run it on non-Apple hardware in the first place, but you'd be surprised just how much hardware it supports.
Of course, it's in violation of the macOS EULA to run it on non-Apple hardware in the first place, but you'd be surprised just how much hardware it supports.