What is nVidia Mac Driver or Web Driver?
Nvidia Mac driver is an additional macOS driver provided by Nvidia itself instead of Apple. Apple pack macOS with its own GPU Kexts, but when Nvidia web driver is installed, Apple’s native GPU Kexts becomes inactive. Nvidia web-driver is required to make Maxwell, and latest Graphics cards work in macOS
Here are some nVidia GeForce Graphics cards which needs Webdriver to function properly in macOS (GTX 750
, GTX 780
, GTX 970, 
GeForce GTX 980
, GTX 1070, GTX 1080 GTX TITAN, & etc)

You can download nVidia Web-driver from this page or Install with Automatic Nvidia web driver Installer.

How to enable Nvidia Web Driver

How to activate Nvidia web-driver with Clover Bootloader or Chameleon Bootloader

Clover Bootloader

• Mount EFI Partition / If you have installed legacy Clover look into /EFI folder for config.plist
• Open /Volumes/EFI/EFI/CLOVER/config.plist with text edit, Xcode, or Plist Editor Pro
• Edit Config.plist  to resemble the changes below this works for Sierra 10.12.3 or above versions

<key>SystemParameters</key>
    <dict>
        <key>InjectKexts</key>
        <string>YES</string>
        <key>InjectSystemID</key>
        <true/>
        <key>NvidiaWeb</key>
        <true/>
    </dict>

However, for older system nvda_drv=1 is required still web driver installer  inject nvda_drv=1 to NVRAM

 <key>Boot</key>
 <dict>
 <key>Arguments</key>
 <string>-v nvda_drv=1</string>
 <key>Debug</key>
 <false/>
 <key>DefaultVolume</key>
 <string>Mac</string>
 <key>Secure</key>
 <false/>
 <key>Timeout</key>
 <integer>5</integer>
 <key>XMPDetection</key>
 <string>Yes</string>
 </dict>

Chameleon Bootloader

• Open /Extra/org.chameleon.Boot.plist with text edit, Xcode, or Plist Editor Pro.
• Edit Config.plist  to resemble the changes below.

<dict>
 <key>Kernel Flags</key>
 <string>-v nvda_drv=1</string>
</dict>

This is enough to get nVidia web-driver working in macOS.

Troubleshooting

Monitor goes to sleep at the end of the boot sequence when using iMac15,1 or iMac17,1 or MacPro 6,1 system definition

Fix: modify the AppleGraphicsDevicePolicy.kext as pointed out by PikeRAlpha here. We have two options, using Clover’s built-in kext patching (preferred) or manually editing the kext. Using Clover to patch the kext on the fly is preferred because it does not get overwritten after each OS X update. If you do it manually, you will have to make the edits after each update.

Method 1: The easy method

Install these two kext Lilu.kext and WhateverGreen.kext into your Library/Extensions folder.

NvidiaGraphicsFixup.kext has been replaced by WhateverGreen.kext, if you have NvidiaGraphicsFixup.kext in your system remove it and install WhateverGreen.kext. 

Method 2:

Use Shilohh’s AGDPfix

Method 3:

NOTE: This method does not work with macOS Sierra 10.12, please use method 1 or 2 above.

1. Open your Clover config.plist using text edit and scroll till you see <key>KernelAndKextPatches</key>
2. In that section you have to add the following:

   <key>KextsToPatch</key>
   <array>
   <dict>
   <key>Comment</key>
   <string>(c)Pike R. Alpha</string>
   <key>Find</key>
   <data>
   Ym9hcmQtaWQ=
   </data>
   <key>Name</key>
   <string>AppleGraphicsDevicePolicy</string>
   <key>Replace</key>
   <data>
   Ym9hcmQtaXg=
   </data>
   </dict>

3. Save your config, and now your kext will be patched when you boot by changing board-id to board-ix.

Method 4:

1. Open Terminal
2. Enter this command (it is one line)

   sudo nano /System/Library/Extensions/AppleGraphicsControl.kext/Contents/PlugIns/AppleGraphicsDevicePolicy.kext/Contents/Info.plist

3. Arrow down to where you see <key>ConfigMap</key>
4. For the iMac15,1 locate the board-id “Mac-42FD25EABCABB274” and change string below it from “Config2” to “none”. For the MacPro6,1 you will do the same thing but for the board-id “Mac-F60DEB81FF30ACF6”. For the iMac17,1 you will have to see which board-id is declared in your config.plist SMBIOS: “Mac-B809C3757DA9BB8D” or “Mac-65CE76090165799A” or “Mac-DB15BD556843C820” and change the appropriate entry to “none”.
5. Save the file by pressing Ctrl+O, then enter.
6. Exit by pressing Ctrl+X
7. Rebuild the kernel cache using the following two commands in Terminal:

   sudo kextcache -system-prelinked-kernel
   sudo kextcache -system-caches
   ​

8. Reboot

• GTX750Ti,  GTX950, GTX960, GTX970, GTX980, GTX980 Ti and Titan X REQUIRE 10.10 or later and the web driver.
• GTX780Ti & GTX Titan Black require 10.9.2 or later and Web Driver