Trying to use any form of GPU acceleration on the latest C1 Pro on top of 10.9.3 on the D700 equipped Mac Pro 2013 results basically in a complete freeze of the system.
This is a further regression introduced by 10.9.3, in 10.9.2 using Auto GPU for display was ok.
Disaponting from Apple and Phase 1.
It seems that Apple is unable to release stable drivers for the D700 6 months after availability and/or that Phase1 may need some Open CL focus.
Cheers,
Bernard