I don't recall for certain which nVidia chip my D630 has, or all the chips nVidia mentions in the Quadro line, but as for mine, they recommend using only the vendor (Dell) supplied driver.
Unfortunately, Dell does not any Windows 8 drivers for this system. You may want to try this Windows Upgrade Assistant to see if your system is able to run Windows 8.
Thank You,
Dell-Jesse L
Dell Social Media and Communities
On a 32 bit windows 8 pro install, DON'T use the latest 32 bit nvidia driver available from Dell.
Use the slightly older 32 bit driver from Dell HERE released 1/19/2007 version 97.46, A01 (which is the same release date as the latest 64 bit driver)
Works with no problem