I use PC Versions of the GTX-980Ti in my 5,1 Mac Pros because there a lot cheaper than the Mac Modified Versions. Because of the Gen 2 PCIe Bus Architecture in those systems the only benefit you would likely see with a 1080Ti is the extra RAM when applying a lot of heavy nodes on clips. You will be less likely to run into the “Out of GPU Memory” error. I saw almost no playback or render performance increase when I went from 980’s to 980Ti’s so I doubt if a 1080Ti will be any better than the 980Ti in that respect.
All my slots are full so I don’t have the luxury of installing a Mac Card like the GT-120 for my GUI. My trick is to initially install the OS and Nvidia Web Drivers with a Mac GT-120 in slot 1. I then turn on Screen Sharing, shut down the system and then put the PC GTX Card into Slot 1. I do this because everytime Apple releases a Security Update my Monitors don’t come up after the reboot until the Nvidia Drivers are updated. I then Screen Share into the system, update the Nvidia Drivers and after the Driver Reboot my Monitors come back up again. It’s also handy when I need to reset the PRAM and the OS Reverts to the Mac Drivers. In that case I can Screen Share in, switch to the Nvidia Web Drivers and after a Reboot once again my Monitors are back in action.
"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more.
Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."