since a certain version of macOs Nvidia must be activated by another way.
As of the 10.10.5 driver there are no longer the checks in the distribution file for system profile and if the hardware is installed. It only checks for the OS X build number.
When your mainboard doesn't have native NVRAM Support, you have to install the newest clover and hit a checkmark into the Installer by selecting EmuVariableUefi-64.
Look at the screen in the attachment
After that reboot your machine, and activate the NVidia Driver --> next reboot
Once rebooted, it should say that you are using the NVIDIA web driver. If it is not working still then you may need to re-run the Clover installer and select "Install RC scripts on target volume".