Nvidia GTX680 and Mojave OS
I recently purchased a Flashed Nvidia GTX680 Video Card for my Mac Pro 5,1 12-core. Card works fine but after updating to Mojave OS I find out there is no update software available from Nvidia for the card to be able to utilize the GPU acceleration built in. Nvidia and Apple are both aware of this and both say updates are coming shortly. In the meantime I basically have a glorified 5770 that can't do anything I purchased it for other than the fact that it is at least compatible to run with Mojave OS.
Make sure to install Latest Nvidia Web Driver before updating to Mojave. This is very important as it is not easy to code it in after the fact. The 680 card will function fine and hopefully they will release the software update soon (Even though the rumor is that Nvidia has already supplied the update to Apple and they are holding on to it for whatever reason)
Mac Pro, macOS Mojave (10.14)