Nvidia GT 740M on Windows 7 Pro x64 problems

Hi, I have recently bought 2 Vostro 5470 laptops.

I have disable the Intel HD Graphics video card in order to use the GT 740M one.

Although the device manager recognizes the Video card ("NVIDIA GeForce GT 740M), when I go to Advanced Video Properties, the information is empty, meaning the "Chip Type", "DAC Type", Adapter String", Bios Information" etc. Additionally, there's a "Vgasave" driver installed.

I have tried to install Microsoft's and Nvidia's drivers with no luck. I have tried to update the BIOS to the latest one (5470A09). Nothing changes. The video effects response is very slow and it is working like a Generic VGA driver.

Can you please help?

Thank you in advance.