Graphics card you have even if it is not 'Metal' it is useful if you ever need to do trouble shooting and need to see If you decide to buy a PC card it will work fine but you will not get those boot screens so hold on to any mac These cards have the mac boot efi which allows you to see the start up screens and the Startup Manager. It would be recommended to get a graphics card that is a Mac edition or has been 'flashed' for Mac, MacOS Catalina does not officially support the 2012 Mac Pro. First thing is that if you buy a Metal capable graphics card you will only be able to upgrade to macOS Mojave.
