I just updated my windows drive in my Mac Pro 2009 flashed to 5,1 and rebooted back into OS 10.12. Usually it boots right into the desktop but this time I saw the Apple logo halfway through the boot along with the progress bar. The graphics card my display is connected to is a PC Card. Asus GTX 750ti. I'm confused as to how I am seeing the boot screen on an unflashed card.