Into the Windows system: Double-click the icon in the lower right corner of the taskbar to enter Realtek HD Audio Manager (Realtek HD Audio Manager). 2: Click on the upper right corner of the "Folder" (file) icon Click the Disable front panel jack detection "of (Close the front panel jack detection). Click "OK" (OK).
If still can't fix thsi issue..Please...
Could you please help to check your case front audio is AC97 or HD audio moulude?
Then re-into the bios to set..
RE-into the os,then re-installed audio driver test again
Realtek Audio Driver V5.10.0.6699 for Windows XP 32bit & 64bit.(WHQL)
http://support.asus.com/Download.aspx?SLanguage=zh-tw&p=1&s=39&m=MAXIMUS%20V%20FORMULA&os=30&ft=4&f_...