I tried this but when booting Linux it didn't give a login screen.  Connecting remotely, X Server was not active so couldn't use the GPU.  I usually have to login on the console for X Server to start.  I had to revert the settings to --adapter=all.  I only have the one video card in this PC but maybe I can try this again when I can make this a secondary card.  I am expecting a new power supply in a few days and should be able to try this after that is installed.