I have upgraded my Dell Studio XPS graphics card from an Nvidia GeForce GTS-240 (OEM) to Nvidia GeForce 620. Now windows says that "No audio device is installed". The PC only boots in Safe Mode, otherwise it gets stuck. After a few maneuvers, now it does not even boot in Safe Mode. Gets stuck on ClassPnp.sys. The old card had one cable connected to it that I was not able to connect to the new card (there is no connector) for it on the new card. Maybe that cable carried sound from the video card to the motherboard? There is a separate SoundBlaster sound card in the PC, and sound worked fine before I upgraded the video card.