That would be because it isn't really a driver
(no .sys), more like an a few files (a .DLL, a .nvu, and one .exe) that go and tell Windows what to do with itself (and add the Nvidia name to a few devices in Device Manager). It is showing as it should and you're not missing anything.
Guessing that this is your motherboard (what you have listed in your specs all Google searches right back to any thread you posted here), GA-73PVM-S2H (rev. 1.0) - GIGABYTE - Product - Motherboard - Overview
if so it is a Nvidia 630i based board and you can ge the latest motherboard drivers
here, NVIDIA DRIVERS 15.49 WHQL
which also includes and updated SMBus (4.74). Even if you install it, other than the version number changing it will still show as "no driver installed".