UPDATE: don’t follow these instructions. While it looks like everything is OK, it causes GPU rendering to fail with the Cycle renderer. 
If you have trouble setting up CUDA on macOS 10.13 High Sierra, you can try installing the latest Nvidia web driver.
Usually, for all macs besides the Mac Pro, you can use the driver included in the OS. But if you install the latest CUDA driver from November 2, 2017, then it won’t recognize the driver that is included with macOS. Not sure exactly who is to blame, but probably just the usual slow communication between giant hardware companies. In this case, maybe the driver included with the Mac is too old and we need a 10.13.1 to get a matching video driver with no fuss.
The mac driver is available from the Nvidia website. It installs a driver manager menu bar extra that let’s you change driver, if necessary, as well as a System Preferences pane that shows you the driver info. Then you will no longer see a compatibility warning in the CUDA preference pane.
