05-08-2012 11:51 PM - edited 05-08-2012 11:53 PM
I also have a Z210 with a Quadro 600 graphics card connected to a 27" panel via DP. Note that the Quadro drivers also load NVIDIA High definition Audio drivers. I also have the Realtek High definition Audio drivers associated with the on-board audio hardware loaded.
The Realtek HD Audio manager is the red speaker icon in the notification area of the task bar but I also have a gray speaker icon associated with the monitor/nvidia drivers.
I need to select the NVIDIA High Def Audio as the default device which associates with my monitor so I can get sound via DP.
Maybe you need to ensure you have updated graphics drivers, onboard sound drivers, monitor drivers/inf.
Then select the monitor
Hope this helps.