Sound Card not detected when laptop boots up with external monitor (mini dp) connected - Alienware 15 R2 (4720HQ)

[sourabhkul]

Hi everyone.
I have an Alienware 15 R2 (i7 4720HQ, 970M, 16GB, FHD) running windows 10.
I have set it up in desktop mode by connecting it to ASUS MG28UQ 4K monitor, mouse and keyboard. The monitor is connected through the laptop's mini dp port.
The problem is that when I boot up the laptop with the monitor connected, the laptop's internal sound card (SoundBlaster Redcon 3di) does not function, and is not available in the audio playback devices menu. The intel display audio works, though.
But when i shut down the laptop, disconnect the monitor, and then boot it back up, the sound card is detected and functional, and stays funtional even after i connect the monitor to laptop after it has booted. It keeps working until i reboot, after rebooting the same thing happens.
Any ideas what might be going wrong?

Things i tried:
reinstalled sound card driver
windows troubleshoot

Thanks in advance

 

[webworkings]

First, make sure that the display audio device is not 'disabled' in Device Manager. When connected through HDMI this should be enabled. If it is disabled, try enabling it and see if that resolves the problem.

Second, I would suggest downloading the latest graphics drivers from Intel. This should also update the HDMI audio drivers, and may fix the problem. You may also need 4th Generation or later CPU graphics drivers. You may want to download Intel's driver updater, to automatically search for drivers.