I also have a Gigabyte GTX680 4GB in my 3,1 running Mojave but I'm getting no display output at all through HDMI or DVI, tried multiple monitors including an official apple cinema display. Is the Gigabyte card Metal compatible? Do I need to flash it with a ROM from the mac edition of the card? Or is that only for boot screen? Does it become Metal compatible after flashing? sorry for all the questions, I'm fairly new at this haha. I checked out the thread above but everyone's talking about EVGA rather than Gigabyte. Feel free to link me to the right place if this has been answered elsewhere. Thanks in advance.