The reason why when you install the driver for the card, where the card is not picked up.
Or the driver fails to complete the install.
First of all you have a Ti version of the 750. it requires for most Ti cards power direct to the card via a 12v six pin Pci-e power connector from your power supply.
Next once checked for power 12v six pin Pci-e power from PSU to card.
Download the latest driver and the bit version from Nvidia.
http://www.geforce.com/drivers
Once downloaded.
Right click on the installer icon for the nvidia driver.
And select run as administrator.