Not sure what destabilized Windows to freeze but a reset was necessary to restore the machine to some level of usefulness.
The reset feature can retain files but programs and drivers are all removed and windows is cleanly installed.
Flaky video card drivers are usually cleaned up easily enough so this probably not causal.
This leaves windows to blame and probably the BIOS on the MSI X470 Gaming Plus. The RAM does not run at better than DDR4-1866 which is well below the DDR4-3200 the memory is rated at.
For some reason, over night. the X470 keep awakening and going back to sleep. This happened several times which suggest some event was active.
Turns out that the Razor software for my keyboard installed a new power plan that is always on. So much for the EPA Energy Star.
The Corsair Link program does not work when the machine is resumed from sleep. Machine has to be rebooted to get the monitoring restored.
BACK TO THE RX 480
Installed the RX 480 as this card is more powerful than the GTX 1060. The cleaned up operating system eliminated a lot of problems.