Thanks! Yeah I get the black screen when I put in 1912. What smbios is that? I'm using 17,1 I believe.
If your current version is macOS 10.12 (16A323), no reason to re-install. If not, delete the install app in Applications (Install macOS Sierra.app) and go to MAS>purchases to download the new version...I have the first GM in my applications and the app store wont let me download the official as it is greyed out and says "Downloaded". Do I have to delete the GM or are they the same things?