Screen shot above is after a successful installation of software and hardware. See my description below.
Nvidia successful installed after 005 and 006 security updates.
005 and 006 security updates installed with the Radeon 5770 still installed.
Swapping out the ATI Radeon for The GTX 1080 Ti was my final action.
My workflow is described below.
Hello All. I just joined moments ago to thank each and everyone of you.
I've been following this thread for weeks. You're a dedicated, talented and impressive group.
More power to you all.
I'm currently back up and running on my GAINWARD Geforce 1080Ti from macvidcards thanks to you all.
I tip my hat.
I followed the post #662 with some deviations due to my specific machine.
I could not safe boot with the shift key nor could I safe boot with the terminal. No safe boot.
I have to hold down the option key on the chime every time my Mac starts as a result of a bootcamp problem last year.
This I believe prevented me from accessing safe mode I think.
Regardless it all worked out as I'm up and running again on my Nvidia card.
Please not I also have my old ATI Radeon 5770 in during this entire process and only swapped it out for my 1080Ti at the very end.
Here is what I did as I hope it may help others.
1. I couldn't safe boot at all as I described above but I went ahead anyway in normal mode.
2. I manually uninstalled all the Cuda and Nvidia files I could find. I also used cCleaner and App Cleaner & Uninstaller. They found extra files.
3. I was on 10.13.6 (17G14019) on my Mac Pro (Mid 2010). So I installed Security update 005 first. This took 45 minutes. Upon successful installation I was now on 10.13.6 (17G14033).
4. I then installed security update 006. This took a further 40 minutes. Upon reboot I was now successfully in 10.13.6 (17G14042). Please note my booting problem is now resolved. I now no longer need to hold down the option key upon the chime during start up. Thank you updates.
Remember the ATI Radeon is in the entire time.
5. I installed the Nvidia driver posted on this thread. (No GPU detected) as the ATI Radeon is installed.
6. I installed the CUDA driver.
7. I shut down the Mac Pro. Took out the ATI Radeon. I then installed my Geforce 1080Ti. I hit the power button and she booted up into dual monitors with no problems.
I hope this will help others. Thanks a million again.
I'll keep in touch of any further developments or not.
Basically I'll let you know its all good and there is nothing to report over the coming days and weeks.