news from my Optiplex780  with the gt710 (Mojave)
Onboard audio works again with rollback AppleHDA 10.13.3 (AudioCodec Optiplex780 in AppleALC has broken since 10.13.4)
HDMI Audio with the gt710 now works with HDMIAudio.kext in Clover /other   Edit: @chris1111 sorry, the first test was still with InjectNvidia=true
now with InjectNvidia=false I have 4 ports and Metal
now everything is perfect with graphics and audio sorry and thanks      Edit2: amazing, the GT710 works in the Optiplex780 with 10.13.6 also native, despite missing Injector iGPU. Also no WhateverGreen needed.