i upgraded my Mac Pro 2009 from High Sierra to Mojave in October. At the same time, since Mojave only supports graphics cards that are Metal-capable, i upgraded my old graphics card to SAPPHIRE Radeon PULSE RX 580 8GB GDDR5, as recommended in Apple website. Since the graphics card is made by 3rd party manufacturer, there's no Apple logo bootup screen until login screen appears. Other than this, my Mac Pro is running very well. Now, i wanted to do a fresh installation of Mojave, i tried to enter recovery mode but no luck, because Mac computer doesn't recognize the 3rd party graphics card in recovery mode. So i put back my old graphic card and i saw recovery mode screen. RX 580 was still in the Mac computer (i connected display cable to RX 580, but there was no visual). When it came to the point to press install Mojave OS, the system said the current graphic card doesn't have metal-capable feature, installation could not proceed. Has anyone come across the same situation and you have solutions? Appreciate if you share some thoughts here!