First of all, thanks Tony, your guide worked perfectly. A few things I've found: I had horrendous artifacts and flashing using any driver (osx and nvidia web) with a gtx550Ti. Swapped to a quadro and it worked really well. I let the machine go to sleep and it wouldn't wake. Odd. Had to force a reboot. Then it shuts down on every boot into the macOS partition, fails with an i/O error, disk could not be verified completely. Having to go for a fresh install. Anyone else had this? No idea what caused it....