Try removing any references to GPU 0 from your xorg.conf
You can do this by reinitializingn (assuming adapter 1 is GPU 1):
aticonfig -f --initial --adapter=1
You can do this by reinitializingn (assuming adapter 1 is GPU 1):
aticonfig -f --initial --adapter=1
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.