Hello guys,
my hack
ga-Z68X-UD3H-B3
Ati 6850 1GB
I7 2700k
I read that the ATI cards do not wake up from sleep, and the only way is to set the bios on the motherboard integrated graphics card as the primary card.
So I tried inserting a DVI cable to the integrated card and hdmi cable to the ATI card all connected to the same monitor. Everything works.
the hassle is to have two connected cables. It also works only leave connected the hdmi cable from ati card to the monitor but then when you turn your hack will see the black screen until the Sierra login screen. For basic configurations with a single operating system would be acceptable, in my case Yosemite use for my Digital Audio Workstation and Sierra for the work I have to leave connected the two cables always.
Finally you might choose to delete forever Ati radeon 6850 card and use only Intel HD3000 for all installations present
If anyone knows a better method exposes him as well.
With my Sierra configuration works fine without special kext than those on Multibeast even iMessage works correctly
See you soon