tell us exactly what colour cables are plugged in at the back from your spkrs and their respective plug colours.
What make/model 5.1 spkrs
Are there any unregistered/yellow highlighted drivers left in "Device Manager"?
If you have a single cable (yellow-end-plug) - you are digital & should be plugged into Yellow? SPDIF socket
Did you stick this 3rd revision sound driver (from asus website > downloads) on your pc or are you using provided cd one?
Realtek Audio Driver V184.108.40.20657 for 32/64bit Windows XP.(WHQL)
Realtek Audio Driver V220.127.116.1157 for 32/64bit Windows Vista, 7 & 8.(WHQL) File Size 140,68 (MBytes) 2012.09.13
update Download from
P2P ASUS - Motherboards- ASUS P9X79 PRO
This too - right up to date
Intel Chipset Software Installation Utility (WHQL)
Support OS : Microsoft Windows 7 & 8 32/64 bit File Size 4,29 (MBytes) 2012.12.11