Here's the fix.
1) Download the Drivers .ISO ( ucs-cxxx-drivers-windows.2.X.XX.iso )
2) Mount the image on your server
3) Browse to the E:\ChipSet\Intel\[Your type of server]\W2K12R2\
4) Run the file you find there ( SetupChipset.exe )
This resolved the bunch of devices missing drivers in 2012R2 for me.
Hope this helps.
... View more