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."
we are a Danish company which builds professional, custom Mac Pro 5.1 with single or dual high-end GPUs, such as 1080Ti and Titan Xps.
I disagree with previous comment saying there is not much to gain.
1) the Pcie 2.0 is basically not a limit in any way for these machines, beside gaming, since there is more than enough bandwidth for anything, even on the x4 link (only 4-6% loss by putting a GPU in slot 3 and 4, and only under extreme stress)
2) the generation difference between Maxwell (9xx series) and Pascal (10x0 series) is amazing.
What is even more amazing is how the Mac Pro 6.1 cannot even compete at all, unless we sell eGPUs together with it.
As an example, a nice specced mac Por 6.1 (2013) 8 Core 3.3Ghz with D500s cannot even playback a 5K 72fps RED RAW clip.
A Mac Pro 5.1 with our modifications can run e.g. VEGA 16GB or 1080Ti, can play an 8K 48fps RED RAW clip at 24fps just fine.