If you are persistently getting "Nvidia Installer Failed" or cannot install or uninstall the PhysX drivers, with the Clean Install option, or with running the PhysX installer separately, this could be a problem with the Windows WMI being corrupt or a registry corruption. There are a few things you can try:

This may be due to a corrupt Windows registry key, try the following Microsoft FixIt:

https://support.microsoft.com/mats/Program_Install_and_Uninstall

If the problem persists, to repair and rebuild this, you can give this elevated this command prompt a try:

1. Open an elavated command prompt. Click Start -> Type CMD -> Right click on CMD from the result -> Click Run as Administrator

2.Type: net stop winmgmt and hit enter
Then go to the C:\Windows\system32\wbem directory and delete the Repository directory

3. Type: net start winmgmt and hit enter.

4. Run the following command one at a time and press enter to execute
cd /d %windir%\system32\wbem
for %i in (*.dll) do regsvr32 -s %i
for %i in (*.exe) do %i /regserver

5. Close all windows and reboot the computer and now try running a clean install of the nvidia driver again.

If the problem still persists, a reinstall of the OS may be in order.