Problem with Gigabyte Z97x Gaming 5

Hi, I bought the motherboard Gigabyte Z97x Gaming 5 a few days ago, but I have a trouble with the sound. The sound is output only from the right side (speakers or headphones), so the left speaker and subwoofer are as if they were off. I have the latest BIOS version (F6). I tried uninstalling and installing DVD drivers, Internet drivers, and predefined Windows drivers too (with all I have the same problem). I also tried three different versions of Windows (10, 8.1 and 7), but the problem persists. I don't know what to do.

Note: The speakers work ok in others motherboards.

Sorry for my bad english and thanks.

Problem with Gigabyte Z97x Gaming 5