Cannot get Onboard SPDIF to show as an available device when Nvidia Graphics drivers

This is for a HTPC.

Recently I have been getting screen flashing issues when I run my HTPC for a period of time. I found that if I bypass my AV receiver [HDMI] straight to my TV I no longer have the issue. I have been successfully running passthrough using my Pioneer receiver for my 5.1 surround for years without any issues. So what I want to do for a temporary solution until I can figure out if it's the graphics card or or my receiver is to go straight to the TV with the HDMI, disable the audio within the Nvidia control panel them use the digital SPDIF on my Gigabytes motherboard. I have tried the Coax and the optical and neither seem to work. I can only get the SPDIF to show as an available device when I completely uninstall all the Nvidia drivers, which of course I need.

All drivers are current.

What am I missing, is there a workaround?

Windows 7 Pro 64 Bit
Gigabyte P55-UD3
Nvidia GeForce GT430