Being cautious and not really trusting High Sierra yet, I installed High Sierra (HS) on a new 1TB drive. When It finished I had one of two monitors working. As far as I can determine, HS does not see the installed MSI GeForce GT 730 graphics card. It attempts to put both of my monitors on a NVIDIA GeForce GT120 card. This results in the monitor that is actually connected to the GT120 card to almost work, and the monitor (which is really a TV with an HDMI input) has a essentially a black screen with some light grey menu text at the top. When I started System Preferences and selected Monitors the small windows that popped up had both monitors listed as connected to the GT120. (??) I have tried for a new driver for the GT 730, but there is none listed on MSI's site. The Menu text at the top of the screen is all smeared on the working monitor as well, as there is no apple icon etc. I have booted back into Sierra on my standard drive to try to find a solution. When I move a window on the monitor connected to the GT120 which sort of works, I see flashing and small fragments of the window show up on the GT730 monitor. My mac is a 2009 Mac Pro, that thinks it is a 2010 Mac Pro ( I had to flash it to get Sierra to load), with 24 GB RAM. I have four drives installed, two 1 TB drives, one 500 GB SSD, and one 2 TB drive I use for Time Machine backup. I am used to Macs just working, so I do not have any idea how to point HS to the GT730. Maybe it is the fact that my Mac Pro even flashed to look like a 2010 MP actually cannot run High sierra? Any ideas?