Is dual audio output possible

There are a number of possible things going wrong here:

1. The on-board sound is still enabled

2. The old on-board sound drivers are still installed

3. Your drivers for the new card aren't updated.

The first thing you need to check is your BIOS. Make sure the on-board sound is disabled. After you've done that and booted into Windows, go into the Device manager and verify the only sound card Windows sees is your new card.

After you've confirmed that Windows sees only your new sound card, go to the manufacturer's website and see if there are updated drivers. If so, download and install them, then reboot and see if that takes care of the problem. If not, and you're still seeing a hang, there may be something else wrong with the motherboard itself, which could be causing the on-board sound not to function as well as the hangs you're seeing.

I don't think the motherboard is to blame.

If your front panel has a USB I/O try to disconnect the USB cable from the motherboard to the front panel. If the static noise is gone try modifying the circuitboard so the ground connectors are no longer connected to the headphone ground pin (HDD use + front panel audio = static noise - Tom's Hardware) (the front panel shares the same ground for USB and audio I/O).