Lost sound after installing NVIDIA FX580

Uninstall the sound in the Device Manager, then restart the PC and when Windows starts it will detect and reinstall the sound.  This fixes a lot of problems.

To access the Device Manager, hold the Windows key down and then press the Pause/Break key.  Only install the actual device, do not uninstall the drivers.

Your suggestion makes perfectly good sense, but no soap.  We even tried uninstalling both the drivers and audio device, no soap.  This conflict has occurred on both Dell machines (identical) we have running.  They were purchsed at the same time and we upgrade identically. Thanks for your input.

If you remove the NVIDIA cards, does the sound come back?  It sounds like the sound and the video card are being assigned the same shared IRQ by Windows. 

Yep, sure does. 

Any idea on how to circumvent or correct this?

Have you contacted PNY (or whoever made the card)?  I see there are certain BIOS settings, etc that they recommend for this card.  Could be a setting or even a driver version for the card that will correct this. 

Bottom line, it's not the PC or the Audio that is really the problem, the problem is the video card compatibility with your system (or settings needed to make it 100% compatible).  The PC does not have to be made compatible with the card, the card must be made compatible with the PC.  Ultimately, it may mean a different video card, that will support what you need to do.

My favorite comparison on these types of things is, that you have Ford (or whatever brand) vehicle and you install a 3rd party (aftermarket) part on the car and it doesn't work properly.  It's not Ford's responsibility to make their car work with that part.  It's the 3rd party vendor that is responsible for their part working (or fitting) properly.

You analogy of heirarchy for this problem is perfect.  I will contact PNY today and see what they say.