Soung stops randomly in Asus xonar STX

Hi everyone,

I installed a brand new Asus xonar STX in my desktop PCIe. The sound stops randomly while playing music or watching movies. It starts working again only after a restart. I have been trying to fix it for more than a week with no success.
Steps I have tried so far:
1. Update the drivers from asus website
2. Installed unixonar drivers
3. Disabled on board audio in BIOS
4. Deleted win 7 and installed Win 8.1
5. Ran chkdsk /b

Also when the sound stops my music player stops playing. I can still play videos with no sound in vlc or MPC but winamp does not work at all as it is audio only player. I am using rca 2-channel out. After the sound stops I can select s/pdif as default device and the sound starts working again (only through s/pdif and not through rca 2-channel), winamp starts playing, everything is fine.
Any help is highly appreciated. Thanks in advance.

You first say you must restart the PC to get sound working, but later say you can enable S/PDIF and it will work. Which is it?

I assume, from your description that you are using the digital S/PDIF output for audio to an external amplifier.??

Did the sound work OK before you installed the Xonar sound card?

One comment. You have a 64 bit OS but only 4GB of RAM. A 64 bit OS uses more basic memory than a 32 bit and for best results the 64 bit should only be used when you have more than 4GB of RAM. Depending on how many applications you have running memory could be an issue and one potential cause of your problems.

I mention the 64 bit/4GB Memory as it can be an issue. The primary purpose for using a 64 bit OS is because you have more than 4GB of RAM. Otherwise 32 bit OS is appropriate.

Back to the problem.
When the sound stops, is the correct playback device still set as default playback device? On regular sound, the "Speakers" are the default playback device. If that is the same on this Xonar card, check that when the sound stops.

If you have a different PCIe slot on the motherboard, move the card to a different slot and see if it makes any difference.

Keep the on board audio disabled in the BIOS to prevent any conflict.