I've got an upgraded 2010 Mac Pro (12-core 3.46Ghz Westmere with 1333mhz RAM) with a flashed NVidia GTX 780 (6GB) attached to an LG Ultrawide display, and 250GB of flash storage attached to a PCIe Marvell RAID card as the boot drive. There are SATA drives filling up the rest of the slots. Originally it was running Yosemite without any issues. Then I upgraded to El Capitan and found that whenever there is a security update, and I need to install the latest NVidia driver, I now have to boot into safe mode, install the driver, and then it will reboot just fine (otherwise it hangs forever on boot). I would like to finally move up to High Sierra and have confirmed that all my apps are Sierra compatible. However, I was wondering if anyone has direct experience installing High Sierra on a machine with a flashed NVidia card (or has any knowledge of issues related to a machine using any of the hardware I have). Thanks!