This is just a headsup that the safari 10 update for El Capitan breaks support for 5k displays such as the dell 27" on a mac pro trash can model. I installed the update this am and video was gone after reboot, I used a lower resolution monitor and then had to reinstall from a time machine backup to get my mac pro functional again. Only 15 wasted hours.... I did call tech support in case it was possible to back out of the uprade, but apparently not. So I guess I'm stuck not updating.