GUI freezes, but I can still use the ctrl-alt-f2 console

[RainyDay]

This was solved by updating the Xorg config to use AMD described in:

What is my GPU really here for? Truely understanding VCPUs and fully ultilizing GPU

Thanks @renehoj! The machine has been up and non-frozen for 8 hours now, so looks like that was it. Typically it was freezing in just a few minutes before.